Add project structure and rules documentation: Introduce guidelines for organizing backend, frontend, and shared components, including rules for services, API routes, clients, and components to ensure a consistent and maintainable codebase.

.cursor/rules/api-routes.mdc

@@ -0,0 +1,32 @@
+---
+globs: app/api/**/*.ts
+---
+
+# API Routes Rules
+
+1. Routes MUST only use services for data access
+2. Routes MUST handle input validation
+3. Routes MUST return typed responses
+4. Routes MUST use proper error handling
+
+Example of correct API route:
+
+```typescript
+import { MyService } from "@/services/my-service";
+
+export async function GET(request: Request) {
+  try {
+    const service = new MyService(pool);
+    const data = await service.getData();
+    return Response.json(data);
+  } catch (error) {
+    return Response.error();
+  }
+}
+```
+
+❌ FORBIDDEN:
+
+- Direct database queries
+- Business logic implementation
+- Untyped responses