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/app/notifications.py

@@ -5,6 +5,7 @@ survive reloads/devices and are produced server-side. First producer is the main
 job. Unread rows never auto-expire; read rows are trimmed past a soft per-user cap so the
 table can't grow without bound for a heavy user.
 """
+
 from sqlalchemy import delete, select
 from sqlalchemy.orm import Session
 
@@ -37,9 +38,7 @@ def create_notification(
     transaction can pass commit=False and commit once themselves."""
     if title is not None and len(title) > TITLE_MAX_LEN:
         title = title[: TITLE_MAX_LEN - 1] + "…"  # clamp to the column limit, add an ellipsis
-    notif = Notification(
-        user_id=user_id, type=type, title=title, body=body, data=data
-    )
+    notif = Notification(user_id=user_id, type=type, title=title, body=body, data=data)
     db.add(notif)
     if commit:
         db.commit()