feat: meter AI usage

JobTrackerApi/Migrations/20260730203422_AddAiUsageMetering.cs

@@ -0,0 +1,23 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace JobTrackerApi.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddAiUsageMetering : Migration
+    {
+        // Intentionally a no-op: StartupInitializationExtensions owns idempotent SQLite/MariaDB
+        // column reconciliation and runs before EF migrations. The snapshot records the model change;
+        // the reconciler performs the provider-safe DDL without duplicate-column failures.
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+        }
+    }
+}