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/sync/runner.py

@@ -4,6 +4,7 @@ Channel/video data is shared across users, so background work acts through a "se
 user" (any user with a stored refresh token) unless a YOUTUBE_API_KEY is configured for
 public reads.
 """
+
 import logging
 import threading
 from concurrent.futures import ThreadPoolExecutor, as_completed
@@ -173,9 +174,7 @@ def run_recent_backfill(
         return {"channels_processed": 0, "videos_added": 0, "reason": "no service user"}
     if channels is None:
         channels = (
-            db.execute(select(Channel).where(Channel.recent_synced_at.is_(None)))
-            .scalars()
-            .all()
+            db.execute(select(Channel).where(Channel.recent_synced_at.is_(None))).scalars().all()
         )
     if max_channels:
         channels = channels[:max_channels]
@@ -325,7 +324,9 @@ def estimate_deep_backfill(db: Session, channels: list[Channel]) -> dict:
 
     total_units = sum(units(c) for c in pending)
     daily_budget = max(
-        1, sysconfig.get_int(db, "quota_daily_budget") - sysconfig.get_int(db, "backfill_quota_reserve")
+        1,
+        sysconfig.get_int(db, "quota_daily_budget")
+        - sysconfig.get_int(db, "backfill_quota_reserve"),
     )
     eta_seconds = int(total_units / daily_budget * 86_400) if pending else 0
     return {