Add PostgreSQL database layer with Kysely and migrations

- Add database.ts with connection pool, Kysely query builder, and migration runner
- Create migrations for users and sessions tables (0001, 0002)
- Implement PostgresAuthStore to replace InMemoryAuthStore
- Wire up database service in services/index.ts

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

express/services/index.ts

@@ -1,15 +1,16 @@
 // services.ts
 
-import { AuthService, InMemoryAuthStore } from "../auth";
+import { AuthService } from "../auth";
 import { config } from "../config";
+import { db, migrate, migrationStatus, PostgresAuthStore } from "../database";
 import { getLogs, log } from "../logging";
 import { AnonymousUser, anonymousUser, type User } from "../user";
 
-//const database = Client({
-
-//})
-
-const database = {};
+const database = {
+    db,
+    migrate,
+    migrationStatus,
+};
 
 const logging = {
     log,
@@ -34,8 +35,8 @@ const session = {
     },
 };
 
-// Initialize auth with in-memory store
-const authStore = new InMemoryAuthStore();
+// Initialize auth with PostgreSQL store
+const authStore = new PostgresAuthStore();
 const auth = new AuthService(authStore);
 
 // Keep this asciibetically sorted