style: apply ruff format across backend + scripts (line-length 100)

Mechanical, whole-tree `ruff format` pass — no behaviour change. Recorded in
.git-blame-ignore-revs (next commit) so git blame skips it.

backend/tests/test_notifications.py

@@ -5,6 +5,7 @@ clamp that string went straight into Notification.title (String(255)) and, at th
 download_gc commit, raised psycopg StringDataRightTruncation — aborting the entire GC run so
 no expiry deletion / LRU eviction / orphan reap ever ran. The clamp trims the title to the
 column limit centrally, defending all callers regardless of DB backend."""
+
 from app.models import Notification, User
 from app.notifications import TITLE_MAX_LEN, create_notification
 
@@ -28,9 +29,7 @@ class _CaptureDB:
 
 def test_title_clamped_to_column_limit():
     long_title = "x" * 2000  # e.g. a reel caption
-    notif = create_notification(
-        _CaptureDB(), user_id=1, type="download_expiring", title=long_title
-    )
+    notif = create_notification(_CaptureDB(), user_id=1, type="download_expiring", title=long_title)
     assert len(notif.title) == TITLE_MAX_LEN
     assert notif.title.endswith("…")
     # The untruncated title still reaches the client via `data`, which is never clamped.
@@ -68,8 +67,6 @@ def test_over_long_title_actually_commits_on_postgres(db):
     user = User(email="reel@example.com")
     db.add(user)
     db.flush()
-    notif = create_notification(
-        db, user_id=user.id, type="download_expiring", title="z" * 2000
-    )
+    notif = create_notification(db, user_id=user.id, type="download_expiring", title="z" * 2000)
     db.refresh(notif)
     assert len(notif.title) == TITLE_MAX_LEN  # persisted, not truncated by the DB