feat(sql): construct Postgres and Oracle providers; MySql/Odbc stay reserved

Widens the two provider gates so an authored `{"provider":"Postgres"}` or
`{"provider":"Oracle"}` binds that provider's own dialect instead of failing
"not available in this build":

- `SqlDriverFactoryExtensions.CreateDialect` gains a Postgres and an Oracle
  arm. There is deliberately no fallback arm — a default resolving to
  SqlServerDialect would construct happily and then emit T-SQL at a Postgres
  or Oracle server. The rejection message now names the three supported and
  the two still-reserved providers.
- `SqlDriverBrowser.DefaultDialectSelector` widens identically, so a provider
  the runtime constructs is also browsable; MySql/Odbc keep resolving to null
  and the caller keeps reporting them as unavailable.

Tests: the existing rejected-provider controls flip from Postgres to MySql
(factory) and Odbc (browser) so the reserved half stays falsifiable, and the
new legs assert the bound dialect TYPE rather than mere construction —
"no throw" alone would pass against a SqlServer fallback.

Doc-comment sweep (contract addition, one line each): the "v1 constructs
SqlServer only" / "reserved for P2" claims in SqlProvider, SqlDriverConfigDto,
ISqlDialect.Provider and SqlServerDialect are now false and were corrected in
the same change.

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Sql.Browser/SqlDriverBrowser.cs

@@ -80,8 +80,8 @@ public sealed class SqlDriverBrowser : IDriverBrowser
     /// <param name="dialectSelector">
     ///     Maps an authored <see cref="SqlProvider"/> onto the dialect that browses it, or <see langword="null"/>
     ///     for a provider this build does not carry. Defaults to <see cref="DefaultDialectSelector"/>
-    ///     (SqlServer only, in v1). A constructor parameter rather than a test hatch: it is also how a P2
-    ///     provider gets added without touching this class.
+    ///     (SqlServer, Postgres and Oracle). A constructor parameter rather than a test hatch: it is also how
+    ///     a further provider gets added without touching this class.
     /// </param>
     /// <param name="environmentReader">
     ///     Reads one environment variable. Defaults to <see cref="Environment.GetEnvironmentVariable(string)"/>.
@@ -117,14 +117,23 @@ public sealed class SqlDriverBrowser : IDriverBrowser
         ConnectionStringEnvironmentPrefix + connectionStringRef;
 
     /// <summary>
-    ///     The providers this build can browse. v1 constructs SQL Server only; every other
-    ///     <see cref="SqlProvider"/> member is a reserved name, so it resolves to <see langword="null"/> and
-    ///     the caller reports it as unavailable rather than crashing on a null dialect.
+    ///     The providers this build can browse — SQL Server, PostgreSQL and Oracle. The remaining
+    ///     <see cref="SqlProvider"/> members (<see cref="SqlProvider.MySql"/>, <see cref="SqlProvider.Odbc"/>)
+    ///     are reserved names, so they resolve to <see langword="null"/> and the caller reports them as
+    ///     unavailable rather than crashing on a null dialect.
+    ///     <para>Kept in step with <c>SqlDriverFactoryExtensions.CreateDialect</c>: a provider the runtime
+    ///     driver constructs but the browser cannot select would leave the operator authoring tags by hand
+    ///     against a database the AdminUI refuses to show them.</para>
     /// </summary>
     /// <param name="provider">The authored provider.</param>
     /// <returns>The dialect, or <see langword="null"/> when this build does not carry the provider.</returns>
-    public static ISqlDialect? DefaultDialectSelector(SqlProvider provider) =>
-        provider == SqlProvider.SqlServer ? new SqlServerDialect() : null;
+    public static ISqlDialect? DefaultDialectSelector(SqlProvider provider) => provider switch
+    {
+        SqlProvider.SqlServer => new SqlServerDialect(),
+        SqlProvider.Postgres => new PostgresDialect(),
+        SqlProvider.Oracle => new OracleDialect(),
+        _ => null,
+    };
 
     /// <inheritdoc />
     /// <exception cref="InvalidOperationException">
@@ -143,12 +152,13 @@ public sealed class SqlDriverBrowser : IDriverBrowser
         var literal = ReadPastedConnectionString(configJson);
         var config = Deserialize(configJson, literal);
 
-        // Provider first: "this build cannot browse Postgres" is true regardless of how the database is
+        // Provider first: "this build cannot browse MySql" is true regardless of how the database is
         // named, and answering it before touching the environment keeps the two failures from masking.
         var dialect = _dialectSelector(config.Provider)
             ?? throw new InvalidOperationException(
-                $"Sql provider '{config.Provider}' is not available in this build; v1 browses "
-                + $"'{SqlProvider.SqlServer}' only.");
+                $"Sql provider '{config.Provider}' is not available in this build; browsing supports "
+                + $"'{SqlProvider.SqlServer}', '{SqlProvider.Postgres}' and '{SqlProvider.Oracle}' "
+                + $"('{SqlProvider.MySql}' and '{SqlProvider.Odbc}' are reserved names).");
 
         var reference = config.ConnectionStringRef;
         var connectionString = ResolveConnectionString(literal, reference);

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Sql.Contracts/SqlDriverConfigDto.cs

@@ -16,7 +16,7 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.Sql.Contracts;
 /// </summary>
 public sealed class SqlDriverConfigDto
 {
-    /// <summary>Which ADO.NET provider/dialect backs this instance. Defaults to <see cref="SqlProvider.SqlServer"/> — the only provider v1 constructs.</summary>
+    /// <summary>Which ADO.NET provider/dialect backs this instance. Defaults to <see cref="SqlProvider.SqlServer"/>; <see cref="SqlProvider.Postgres"/> and <see cref="SqlProvider.Oracle"/> are also constructed.</summary>
     public SqlProvider Provider { get; init; } = SqlProvider.SqlServer;
 
     /// <summary>

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Sql.Contracts/SqlProvider.cs

@@ -1,21 +1,25 @@
 namespace ZB.MOM.WW.OtOpcUa.Driver.Sql.Contracts;
 
-/// <summary>Which ADO.NET provider/dialect backs a Sql driver instance. v1 constructs only SqlServer.</summary>
+/// <summary>
+///     Which ADO.NET provider/dialect backs a Sql driver instance. <b>Constructed:</b> SqlServer, Postgres,
+///     Oracle — each over a fully managed provider package, no native client install. <b>Reserved:</b> MySql
+///     and Odbc are declared names only; authoring one fails at driver construction and at browse.
+/// </summary>
 public enum SqlProvider
 {
-    /// <summary>Microsoft SQL Server via <c>Microsoft.Data.SqlClient</c> — the only provider v1 constructs.</summary>
+    /// <summary>Microsoft SQL Server via <c>Microsoft.Data.SqlClient</c>.</summary>
     SqlServer,
 
-    /// <summary>PostgreSQL (Npgsql) — reserved for P2; not constructed in v1.</summary>
+    /// <summary>PostgreSQL via the managed <c>Npgsql</c> provider.</summary>
     Postgres,
 
-    /// <summary>MySQL / MariaDB — reserved; not constructed in v1.</summary>
+    /// <summary>MySQL / MariaDB — reserved; no dialect ships, so this is not constructed.</summary>
     MySql,
 
-    /// <summary>Generic ODBC — reserved for P2; not constructed in v1.</summary>
+    /// <summary>Generic ODBC — reserved; no dialect ships, so this is not constructed.</summary>
     Odbc,
 
-    /// <summary>Oracle — reserved; not constructed in v1.</summary>
+    /// <summary>Oracle Database via the fully managed <c>Oracle.ManagedDataAccess.Core</c> provider.</summary>
     Oracle,
 }
 

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Sql.Dialect/ISqlDialect.cs

@@ -28,7 +28,11 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.Sql;
 /// </summary>
 public interface ISqlDialect
 {
-    /// <summary>Which backend this dialect speaks. v1 constructs <see cref="SqlProvider.SqlServer"/> only.</summary>
+    /// <summary>
+    ///     Which backend this dialect speaks. One implementation ships per constructed
+    ///     <see cref="SqlProvider"/> member — <see cref="SqlProvider.SqlServer"/>,
+    ///     <see cref="SqlProvider.Postgres"/> and <see cref="SqlProvider.Oracle"/>.
+    /// </summary>
     SqlProvider Provider { get; }
 
     /// <summary>

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Sql.Dialect/SqlServerDialect.cs

@@ -7,7 +7,7 @@ using ZB.MOM.WW.OtOpcUa.Driver.Sql.Contracts;
 namespace ZB.MOM.WW.OtOpcUa.Driver.Sql;
 
 /// <summary>
-///     Microsoft SQL Server dialect (design §2.2) — the only provider v1 constructs. Bracket quoting,
+///     Microsoft SQL Server dialect (design §2.2) — the default provider. Bracket quoting,
 ///     <c>INFORMATION_SCHEMA</c> catalog SQL, and the design §3.7 type-family map.
 ///     <para>Stateless and immutable, so a single instance is safely shared by the driver's poll reader and
 ///     the AdminUI browse session.</para>

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Sql/SqlDriverFactoryExtensions.cs

@@ -201,17 +201,27 @@ public static class SqlDriverFactoryExtensions
 
     /// <summary>
     ///     Selects the provider seam.
-    ///     <para>v1 constructs <see cref="SqlProvider.SqlServer"/> only. The other members exist on the shipped
-    ///     enum as reserved names; authoring one is a config mistake that must fail at construction with a
-    ///     message that says so, rather than silently degrading to T-SQL against a non-SQL-Server database.</para>
+    ///     <para>This build constructs <see cref="SqlProvider.SqlServer"/>, <see cref="SqlProvider.Postgres"/>
+    ///     and <see cref="SqlProvider.Oracle"/>. <see cref="SqlProvider.MySql"/> and
+    ///     <see cref="SqlProvider.Odbc"/> remain reserved names on the shipped enum; authoring one is a config
+    ///     mistake that must fail at construction with a message that says so, rather than silently degrading
+    ///     to another backend's SQL dialect against a database that does not speak it.</para>
+    ///     <para><b>Every arm returns that provider's OWN dialect — there is no fallback arm.</b> A default
+    ///     that resolved to <see cref="SqlServerDialect"/> would construct happily and then emit T-SQL
+    ///     (<c>INFORMATION_SCHEMA</c>, <c>TOP 1</c>, <c>@</c> markers) at a Postgres or Oracle server, which
+    ///     fails at poll time as an unintelligible provider error rather than here as a config error.</para>
     /// </summary>
     private static ISqlDialect CreateDialect(SqlProvider provider, string driverInstanceId)
         => provider switch
         {
             SqlProvider.SqlServer => new SqlServerDialect(),
+            SqlProvider.Postgres => new PostgresDialect(),
+            SqlProvider.Oracle => new OracleDialect(),
             _ => throw new InvalidOperationException(
                 $"Sql driver config for '{driverInstanceId}' names provider '{provider}', which is not " +
-                $"available in this build. Only '{nameof(SqlProvider.SqlServer)}' is supported."),
+                $"available in this build. Supported: '{nameof(SqlProvider.SqlServer)}', " +
+                $"'{nameof(SqlProvider.Postgres)}', '{nameof(SqlProvider.Oracle)}'. Reserved (declared on " +
+                $"the enum but not implemented): '{nameof(SqlProvider.MySql)}', '{nameof(SqlProvider.Odbc)}'."),
         };
 
     /// <summary>