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>

.githooks/pre-commit

@@ -4,6 +4,14 @@
 
 REPO_ROOT="$(git rev-parse --show-toplevel)"
 
+# Resolve Docker socket — the git hook environment may not inherit the active
+# Docker context, so we probe common socket paths explicitly.
+if [ -S "/Users/$USER/.docker/run/docker.sock" ]; then
+  export DOCKER_HOST="unix:///Users/$USER/.docker/run/docker.sock"
+elif [ -S "/var/run/docker.sock" ]; then
+  export DOCKER_HOST="unix:///var/run/docker.sock"
+fi
+
 # Collect staged files on the host and pass them into the container as arguments
 STAGED=$(git diff --cached --name-only --diff-filter=ACM)