Add PDF document service with AI extraction and per-app settings

- New `features/doc-service` FastAPI microservice: PDF upload, async
  text extraction (pdfplumber), AI classification via Anthropic/Ollama/
  LM Studio, per-user categories, file download
- Alembic migration isolated with `alembic_version_doc_service` table
- Main backend: httpx proxy routers for /api/documents/* and
  /api/documents/categories/*, admin settings API at /api/settings/*
- Runtime config in /config/doc_service_config.json (shared Docker
  volume); api_key masking on reads; atomic write with os.replace()
- Frontend: DocumentsPage, DocumentAdminSettingsPage, updated AppsPage
  launcher hub, simplified Nav (removed Settings link), new routes
- docker-compose: doc-service service, doc_data + app_config volumes,
  removed internal:true from backend-net for outbound AI API calls
- Fix pre-commit hook: probe Docker socket path so git subprocess picks
  up Docker Desktop on macOS
- Fix security_check.py: use sys.executable for bandit so venv python
  is used instead of system python

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

scripts/security_check.py

@@ -166,7 +166,7 @@ def run_bandit(py_files: list[Path]) -> tuple[bool, str]:
     if not py_files:
         return True, ""
     result = subprocess.run(
-        ["python", "-m", "bandit", "-q", "-ll", "--", *[str(f) for f in py_files]],
+        [sys.executable, "-m", "bandit", "-q", "-ll", "--", *[str(f) for f in py_files]],
         capture_output=True, text=True
     )
     passed = result.returncode == 0