Fix backend test failures: set PYTHONPATH and ensure pytest-asyncio installed

Author: vuneum

.github/workflows/ci.yml

@@ -65,6 +65,10 @@ jobs:
         working-directory: backend
         run: pip install -e ".[dev]"
 
+      - name: Install pytest-asyncio
+        working-directory: backend
+        run: pip install pytest-asyncio>=0.21
+
       - name: Lint backend (ruff)
         working-directory: backend
         run: ruff check .
@@ -75,6 +79,7 @@ jobs:
           DATABASE_URL: postgresql+asyncpg://aaip:aaip_test@localhost:5432/aaip_test
           OPENROUTER_API_KEY: ${{ secrets.OPENROUTER_API_KEY }}
           AAIP_DEV_MODE: "true"
+          PYTHONPATH: .
         run: pytest ../tests/backend/ -v --tb=short
 
   # ─────────────────────────────────────────