feat(v5.2.0): finalize Infrastructure & Polish (tests isolation, xdist, lint, CI)

tests/conftest.py: mutate the settings singleton (instead of rebinding) so DB + backup dir are isolated per test -> pytest-xdist safe.
Real backup tests (snapshot/prune/admin API) and OAuth mock tests (Gitea/GitHub/link) replace the previous skips.
init_db() now also creates webhook_subscriptions (full schema without the FastAPI lifespan).
ruff check is clean; .eslintrc.json migrated to eslint.config.mjs (flat config).
CI: lint job (ruff + eslint), parallel tests (-n auto), run on every branch push.
VERSION 5.11.1.

app/routers/my_tasks.py

@@ -121,7 +121,7 @@ async def my_tasks_dashboard(request: Request, view: str = "all", days: int = 7)
 async def my_tasks_api(request: Request, view: str = "all", days: int = 7):
     """API: return my tasks as JSON."""
     user = _get_current_user(request)
-    user_login = user.get("login", "admin") if user else "admin"
+    user.get("login", "admin") if user else "admin"
 
     with get_conn() as conn:
         collections = conn.execute("SELECT * FROM collections ORDER BY name").fetchall()