[BUG7] Quote RETURNING clause PK column in INSERT codegen + 0.9.3-beta

PostgresCli.GenerateInsertMethod and GenerateInsertTransactionOverload
hard-coded `RETURNING id` (lowercase) in the emitted INSERT SQL.

For tables whose PK column is PascalCase (e.g. "Id", "PatientId")
this fails at runtime with:

  ERROR:  column "id" does not exist

because Postgres lower-cases unquoted identifiers and the actual PK
column name is case-sensitive (it was created with quoted ident).

Fix: emit `RETURNING ""{table.PrimaryKeyColumns[0]}""` (verbatim
escape) so the RETURNING clause references the real PK column with
its case preserved. Falls back to `RETURNING 1` for tables with no
configured primary key. Same fix applied to both the NpgsqlConnection
overload and the IDbTransaction overload of Insert{Table}Async.

Verified locally: regen of Clinical fhir_PatientOperations.g.cs now
emits `RETURNING ""Id""`, INSERT round-trips through Postgres
without 'column id does not exist' error.

Bumps Directory.Build.props Version to 0.9.3-beta.

Author: Christian Findlay

DataProvider/DataProvider/PostgresCli.cs

@@ -851,6 +851,14 @@ string pascalName
         // case-folding.
         var colNames = string.Join(", ", insertable.Select(c => $"\"\"{c.Name}\"\""));
         var paramNames = string.Join(", ", insertable.Select(c => $"@{c.Name}"));
+        // BUG7 fix: RETURNING clause must reference the actual primary-key
+        // column name, quoted for case-folding survival. The previous hard-
+        // coded `RETURNING id` failed at runtime on tables whose PK column is
+        // PascalCase (e.g. "Id") with `column "id" does not exist`.
+        var returningClause =
+            table.PrimaryKeyColumns.Count > 0
+                ? $"RETURNING \"\"{table.PrimaryKeyColumns[0]}\"\""
+                : "RETURNING 1";
 
         _ = sb.AppendLine("        const string sql = @\"");
         _ = sb.AppendLine(
@@ -859,7 +867,7 @@ string pascalName
         );
         _ = sb.AppendLine(CultureInfo.InvariantCulture, $"            VALUES ({paramNames})");
         _ = sb.AppendLine("            ON CONFLICT DO NOTHING");
-        _ = sb.AppendLine("            RETURNING id\";");
+        _ = sb.AppendLine(CultureInfo.InvariantCulture, $"            {returningClause}\";");
         _ = sb.AppendLine();
         _ = sb.AppendLine("        try");
         _ = sb.AppendLine("        {");
@@ -923,6 +931,11 @@ string pascalName
         // as primary Insert method above.
         var colNames = string.Join(", ", insertable.Select(c => $"\"\"{c.Name}\"\""));
         var paramNames = string.Join(", ", insertable.Select(c => $"@{c.Name}"));
+        // BUG7 fix: same RETURNING fix as the NpgsqlConnection overload.
+        var returningClause =
+            table.PrimaryKeyColumns.Count > 0
+                ? $"RETURNING \"\"{table.PrimaryKeyColumns[0]}\"\""
+                : "RETURNING 1";
 
         _ = sb.AppendLine();
         _ = sb.AppendLine("    /// <summary>");
@@ -945,7 +958,7 @@ string pascalName
         );
         _ = sb.AppendLine(CultureInfo.InvariantCulture, $"            VALUES ({paramNames})");
         _ = sb.AppendLine("            ON CONFLICT DO NOTHING");
-        _ = sb.AppendLine("            RETURNING id\";");
+        _ = sb.AppendLine(CultureInfo.InvariantCulture, $"            {returningClause}\";");
         _ = sb.AppendLine();
         _ = sb.AppendLine("        if (transaction.Connection is not NpgsqlConnection conn)");
         _ = sb.AppendLine("        {");

Directory.Build.props

@@ -4,7 +4,7 @@
     <NuGetAudit>false</NuGetAudit>
     <NuGetAuditMode>disabled</NuGetAuditMode>
     <RestoreAuditProperties>false</RestoreAuditProperties>
-    <Version>0.9.2-beta</Version>
+    <Version>0.9.3-beta</Version>
     <Authors>ChristianFindlay</Authors>
     <Company>MelbourneDeveloper</Company>
     <PackageLicenseExpression>MIT</PackageLicenseExpression>