fix(configuration-database): resolve ConfigurationDatabase-013,014 — fail-fast on missing key ring, single converter local; ConfigurationDatabase-012 left open (cross-module design decision)

tests/ScadaLink.ConfigurationDatabase.Tests/SqliteTestHelper.cs

@@ -1,3 +1,4 @@
+using Microsoft.AspNetCore.DataProtection;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.EntityFrameworkCore.Diagnostics;
 using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
@@ -10,10 +11,16 @@ namespace ScadaLink.ConfigurationDatabase.Tests;
 /// Test DbContext that adapts SQL Server-specific features for SQLite:
 /// - Maps DateTimeOffset to sortable ISO 8601 strings (SQLite has no native DateTimeOffset ORDER BY)
 /// - Replaces SQL Server RowVersion with a nullable byte[] column (SQLite can't auto-generate rowversion)
+///
+/// Constructed with an explicit ephemeral Data Protection provider so secret-bearing
+/// columns are write-capable in tests. The schema-only no-provider constructor would
+/// throw on a secret-column write (ConfigurationDatabase-013); passing a provider here
+/// makes the test fixture's intent explicit at the call site.
 /// </summary>
 public class SqliteTestDbContext : ScadaLinkDbContext
 {
-    public SqliteTestDbContext(DbContextOptions<ScadaLinkDbContext> options) : base(options)
+    public SqliteTestDbContext(DbContextOptions<ScadaLinkDbContext> options)
+        : base(options, new EphemeralDataProtectionProvider())
     {
     }