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>

features/doc-service/alembic/env.py

@@ -0,0 +1,55 @@
+import asyncio
+from logging.config import fileConfig
+
+from alembic import context
+from sqlalchemy.ext.asyncio import create_async_engine
+
+from app.core.config import settings
+from app.database import Base
+import app.models  # noqa: F401 — registers Document, DocumentCategory, CategoryAssignment
+
+config = context.config
+config.set_main_option("sqlalchemy.url", settings.DATABASE_URL)
+
+if config.config_file_name:
+    fileConfig(config.config_file_name)
+
+target_metadata = Base.metadata
+
+# Separate version table — must not collide with the main backend's alembic_version table.
+VERSION_TABLE = "alembic_version_doc_service"
+
+
+def run_migrations_offline():
+    context.configure(
+        url=settings.DATABASE_URL,
+        target_metadata=target_metadata,
+        literal_binds=True,
+        dialect_opts={"paramstyle": "named"},
+        version_table=VERSION_TABLE,
+    )
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def do_run_migrations(connection):
+    context.configure(
+        connection=connection,
+        target_metadata=target_metadata,
+        version_table=VERSION_TABLE,
+    )
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+async def run_migrations_online():
+    engine = create_async_engine(settings.DATABASE_URL)
+    async with engine.connect() as conn:
+        await conn.run_sync(do_run_migrations)
+    await engine.dispose()
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    asyncio.run(run_migrations_online())