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_download_limits.py

@@ -9,6 +9,7 @@
 Uses the `db` fixture (real Postgres) — skipped when no database is reachable. `_claim_job` runs in
 its OWN session, so every test COMMITS its setup before calling it.
 """
+
 from app.models import DownloadJob, DownloadQuota, MediaAsset, User
 from app.worker import _claim_job
 
@@ -28,9 +29,7 @@ def _job(db, user_id, queue_pos, status="queued", asset_id=None):
 
 
 def _asset(db, status, ref):
-    a = MediaAsset(
-        source_kind="url", source_ref=ref, format_sig="s", status=status, ref_count=1
-    )
+    a = MediaAsset(source_kind="url", source_ref=ref, format_sig="s", status=status, ref_count=1)
     db.add(a)
     db.flush()
     return a
@@ -50,12 +49,15 @@ def _quota(db, user_id, max_concurrent, unlimited=False):
 
 # --- #2 · claim fairness --------------------------------------------------------------------
 
+
 def test_capped_user_flood_does_not_starve_users_behind_the_window(db):
     a = User(email="flooder@example.com")
     b = User(email="waiter@example.com")
     db.add_all([a, b])
     db.flush()
-    _quota(db, a.id, max_concurrent=1)  # A: 1 concurrent, already running one -> all A's queued are ineligible
+    _quota(
+        db, a.id, max_concurrent=1
+    )  # A: 1 concurrent, already running one -> all A's queued are ineligible
     _quota(db, b.id, max_concurrent=3)
     _job(db, a.id, queue_pos=0, status="running")
     for i in range(1, 61):  # A floods the FRONT with far more than the 50-row fetch window
@@ -122,10 +124,14 @@ def test_job_whose_asset_is_already_downloading_is_skipped(db):
     u = User(email="asset-excl@example.com")
     db.add(u)
     db.flush()
-    _quota(db, u.id, max_concurrent=5)  # high → the ASSET rule, not the per-user rule, does the excluding
+    _quota(
+        db, u.id, max_concurrent=5
+    )  # high → the ASSET rule, not the per-user rule, does the excluding
     busy = _asset(db, status="downloading", ref="busy")
     free = _asset(db, status="pending", ref="free")
-    _job(db, u.id, queue_pos=1, status="running", asset_id=busy.id)  # the holder actually downloading it
+    _job(
+        db, u.id, queue_pos=1, status="running", asset_id=busy.id
+    )  # the holder actually downloading it
     competitor = _job(db, u.id, queue_pos=2, asset_id=busy.id)  # same asset — must be skipped
     behind = _job(db, u.id, queue_pos=3, asset_id=free.id)  # different asset — should be served
     db.commit()
@@ -149,6 +155,7 @@ def test_unlimited_user_is_never_excluded(db):
 
 # --- #3 · list cap --------------------------------------------------------------------------
 
+
 def test_list_downloads_is_capped(db, monkeypatch):
     from app.routes import downloads as dl