feat(localdb): rewire SiteEventLogger onto the consolidated site database

Completes Task 5a of the LocalDb Phase 1 adoption plan. The GUID-id half landed
with Task 2 (727fa48c) because leaving it out would have committed a writer that
could not satisfy site_events.id NOT NULL; this is the connection half, which
was blocked on Task 3.

SiteEventLogger owned a SqliteConnection built from SiteEventLogOptions
.DatabasePath. It now takes ILocalDb and gets that connection from
CreateConnection() - already open, pragma-configured, and carrying the
zb_hlc_next() UDF that site_events' capture triggers call. It still owns and
disposes the connection; WithConnection's signature and locking semantics are
untouched, so EventLogQueryService and EventLogPurgeService are unaffected.

The connectionStringOverride seam is deleted rather than preserved. site_events
is a replicated table, so a raw connection lacks the UDF and fails closed on
every insert - an override could only produce a logger that cannot write. It had
no callers outside this class (the connectionStringOverride hits elsewhere in the
tree belong to SqliteAuditWriter, a different type).

Tests: a shared TestLocalDb helper gives each fixture a real ILocalDb over a temp
file. Real rather than stubbed on purpose - a stub handing back a bare
SqliteConnection would pass today and fail closed the moment the table is
registered, which is exactly the silent-wiring failure mode this family has hit
three times. ServiceWiringTests' DI path also needed AddZbLocalDb, mirroring
SiteServiceRegistration.

Verified: build 0 warnings; SiteEventLogging 70/70, Host 294/294,
SiteRuntime 530/530.

Claude-Session: https://claude.ai/code/session_01BL2Vu1ESDQ9SCN4gVKkdts

tests/ZB.MOM.WW.ScadaBridge.SiteEventLogging.Tests/TestLocalDb.cs

@@ -0,0 +1,70 @@
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using ZB.MOM.WW.LocalDb;
+
+namespace ZB.MOM.WW.ScadaBridge.SiteEventLogging.Tests;
+
+/// <summary>
+/// A real <see cref="ILocalDb"/> over a temp file, for tests that construct a
+/// <see cref="SiteEventLogger"/> directly.
+/// </summary>
+/// <remarks>
+/// <para>
+/// <see cref="SiteEventLogger"/> takes <see cref="ILocalDb"/> rather than a connection
+/// string, and there is no in-memory mode — <c>LocalDbOptions.Path</c> is a filesystem
+/// path. A real one is used rather than a stub on purpose: connections handed out by
+/// <c>ILocalDb</c> carry the <c>zb_hlc_next()</c> UDF that <c>site_events</c>' capture
+/// triggers call, so a stub returning a bare <c>SqliteConnection</c> would pass these
+/// tests while failing closed the moment the table is registered for replication.
+/// </para>
+/// <para>
+/// No <c>onReady</c> callback and no <c>RegisterReplicated</c>: the logger's own
+/// <c>InitializeSchema</c> creates the table, which is what keeps a directly-constructed
+/// logger self-sufficient. Registration is the host's job
+/// (<c>SiteLocalDbSetup.OnReady</c>).
+/// </para>
+/// </remarks>
+public sealed class TestLocalDb : IDisposable
+{
+    private readonly ServiceProvider _provider;
+
+    private TestLocalDb(ServiceProvider provider, ILocalDb db)
+    {
+        _provider = provider;
+        Db = db;
+    }
+
+    /// <summary>The live local database.</summary>
+    public ILocalDb Db { get; }
+
+    /// <summary>Opens a local database at <paramref name="databasePath"/>.</summary>
+    public static TestLocalDb Create(string databasePath)
+    {
+        var configuration = new ConfigurationBuilder()
+            .AddInMemoryCollection(new Dictionary<string, string?>
+            {
+                ["LocalDb:Path"] = databasePath,
+            })
+            .Build();
+
+        var provider = new ServiceCollection()
+            .AddZbLocalDb(configuration)
+            .BuildServiceProvider();
+
+        return new TestLocalDb(provider, provider.GetRequiredService<ILocalDb>());
+    }
+
+    /// <summary>
+    /// Deletes <paramref name="databasePath"/> and its WAL sidecars. Call only after the
+    /// owning <see cref="TestLocalDb"/> is disposed — the master connection anchors the WAL.
+    /// </summary>
+    public static void DeleteFiles(string databasePath)
+    {
+        foreach (var suffix in new[] { "", "-wal", "-shm" })
+        {
+            try { File.Delete(databasePath + suffix); } catch { /* best effort */ }
+        }
+    }
+
+    public void Dispose() => _provider.Dispose();
+}