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/alembic/versions/0016_video_maintenance.py

@@ -10,6 +10,7 @@ the validation lifecycle (last_checked_at for rolling re-validation; unavailable
 unavailable_reason to flag a video as currently unplayable — hidden from the feed
 immediately, hard-deleted after a grace period). Purely additive; all columns nullable.
 """
+
 from typing import Sequence, Union
 
 import sqlalchemy as sa
@@ -26,7 +27,9 @@ def upgrade() -> None:
     op.add_column("videos", sa.Column("privacy_status", sa.String(length=16), nullable=True))
     op.add_column("videos", sa.Column("upload_status", sa.String(length=16), nullable=True))
     op.add_column("videos", sa.Column("last_checked_at", sa.DateTime(timezone=True), nullable=True))
-    op.add_column("videos", sa.Column("unavailable_since", sa.DateTime(timezone=True), nullable=True))
+    op.add_column(
+        "videos", sa.Column("unavailable_since", sa.DateTime(timezone=True), nullable=True)
+    )
     op.add_column("videos", sa.Column("unavailable_reason", sa.String(length=24), nullable=True))
     op.create_index("ix_videos_last_checked_at", "videos", ["last_checked_at"])
     op.create_index("ix_videos_unavailable_since", "videos", ["unavailable_since"])