docs: use pnpm instead of npm in dev commands

AGENTS.md

@@ -163,7 +163,7 @@ Every sub-phase follows **test-driven delivery**:
 **Enforcement**:
 - Each Implementation Task in a sub-phase plan must list its test file(s)
 - Tests must be in the `backend/app/test/` or `frontend/src/test/` directory
-- Pre-commit: `pytest` must pass for backend, `npm test` for frontend
+- Pre-commit: `pytest` must pass for backend, `pnpm test` for frontend
 
 ### Sub-Phase Plan Template
 
@@ -219,7 +219,7 @@ def test_query_with_real_llm():
 ```bash
 # Dev
 backend:  uvicorn app.main:app --reload --port 8000
-frontend: npm run dev
+frontend: pnpm run dev
 
 # Integration tests (TestClient, real DB, only external APIs mocked)
 backend:  cd backend && pytest app/test/test_phase*.py -v

README.md

@@ -13,8 +13,8 @@ uvicorn app.main:app --host 0.0.0.0 --port 8000 --reload
 
 # Frontend
 cd frontend
-npm install
-npm run dev
+pnpm install
+pnpm run dev
 ```
 
 Backend → `http://localhost:8000` | Frontend → `http://localhost:5173`