Add integration tests for migration categories and execution

- Implemented MigrationCategoryTests to validate migration categorization for startup, release, seed, and data migrations.
- Added tests for edge cases, including null, empty, and whitespace migration names.
- Created StartupMigrationHostTests to verify the behavior of the migration host with real PostgreSQL instances using Testcontainers.
- Included tests for migration execution, schema creation, and handling of pending release migrations.
- Added SQL migration files for testing: creating a test table, adding a column, a release migration, and seeding data.

src/Scanner/__Libraries/StellaOps.Scanner.EntryTrace/Runtime/EntryTraceRuntimeReconciler.cs

@@ -252,7 +252,7 @@ public sealed class EntryTraceRuntimeReconciler
             ? EntryTraceUnknownReason.RuntimeMatch
             : EntryTraceUnknownReason.RuntimeMismatch;
 
-        var chain = process is null ? null : BuildProcessChain(procGraph, process.Value);
+        var chain = process is null ? null : BuildProcessChain(procGraph, process);
 
         var message = result.Level == ConfidenceLevel.High
             ? $"Runtime process '{runtimePath}' matches EntryTrace prediction '{predictedPath}'."