TASK-001: Setup FastAPI project structure

- Fixed main.py to include all route routers (posts, users, comments, feed)
- Renamed app/models.py to app/schemas.py and split into proper schema modules
- Fixed schema imports in routes
- Updated app/models/__init__.py to properly export SQLAlchemy models
- Fixed database imports in route files
- App imports and runs correctly

app/routes/feed.py

@@ -7,7 +7,7 @@ from fastapi.security import HTTPAuthorizationCredentials, HTTPBearer
 
 from app.auth import get_current_user_id
 from app.database import get_db, row_to_dict
-from app.models import FeedResponse, PostResponse
+from app.schemas import FeedResponse, PostResponse
 
 router = APIRouter(prefix="/feed", tags=["Feed"])
 security = HTTPBearer()