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_plex_sync_prune.py

@@ -5,6 +5,7 @@ non-empty listing so a transient Plex glitch (an empty page) can never wipe a wh
 DB lane (`db` fixture) — skipped without Postgres. Drives `_sync_movies` / `_sync_shows` directly
 with a stub Plex (the same seam the overlay test uses), so no live server is needed.
 """
+
 from sqlalchemy import select
 
 from app.models import (
@@ -63,10 +64,12 @@ def _seed_movies(db):
     db.add(user)
     db.flush()
     # A watch-state on EACH movie: the kept one's must survive, the pruned one's must cascade away.
-    db.add_all([
-        PlexState(user_id=user.id, item_id=m1.id, status="watched"),
-        PlexState(user_id=user.id, item_id=m2.id, status="watched"),
-    ])
+    db.add_all(
+        [
+            PlexState(user_id=user.id, item_id=m1.id, status="watched"),
+            PlexState(user_id=user.id, item_id=m2.id, status="watched"),
+        ]
+    )
     db.commit()
     return lib, m1.id, m2.id, user.id
 
@@ -132,22 +135,48 @@ def test_show_prune_removes_stale_show_season_and_episode(db):
     se2 = PlexSeason(rating_key="se2", show_id=s2.id, season_number=1)
     db.add_all([se1, se2])
     db.flush()
-    e1 = PlexItem(rating_key="e1", library_id=lib.id, kind="episode", title="Kept Ep",
-                  show_id=s1.id, season_id=se1.id, season_number=1, episode_number=1)
-    e2 = PlexItem(rating_key="e2", library_id=lib.id, kind="episode", title="Gone Ep",
-                  show_id=s2.id, season_id=se2.id, season_number=1, episode_number=1)
+    e1 = PlexItem(
+        rating_key="e1",
+        library_id=lib.id,
+        kind="episode",
+        title="Kept Ep",
+        show_id=s1.id,
+        season_id=se1.id,
+        season_number=1,
+        episode_number=1,
+    )
+    e2 = PlexItem(
+        rating_key="e2",
+        library_id=lib.id,
+        kind="episode",
+        title="Gone Ep",
+        show_id=s2.id,
+        season_id=se2.id,
+        season_number=1,
+        episode_number=1,
+    )
     db.add_all([e1, e2])
     db.commit()
 
     # Plex now lists only s1's subtree.
-    stub = _StubPlex({
-        _TYPE_SHOW: [{"ratingKey": "s1", "title": "Kept Show"}],
-        _TYPE_SEASON: [{"ratingKey": "se1", "parentRatingKey": "s1", "index": 1, "title": "Season 1"}],
-        _TYPE_EPISODE: [{
-            "ratingKey": "e1", "grandparentRatingKey": "s1", "parentRatingKey": "se1",
-            "parentIndex": 1, "index": 1, "title": "Kept Ep",
-        }],
-    })
+    stub = _StubPlex(
+        {
+            _TYPE_SHOW: [{"ratingKey": "s1", "title": "Kept Show"}],
+            _TYPE_SEASON: [
+                {"ratingKey": "se1", "parentRatingKey": "s1", "index": 1, "title": "Season 1"}
+            ],
+            _TYPE_EPISODE: [
+                {
+                    "ratingKey": "e1",
+                    "grandparentRatingKey": "s1",
+                    "parentRatingKey": "se1",
+                    "parentIndex": 1,
+                    "index": 1,
+                    "title": "Kept Ep",
+                }
+            ],
+        }
+    )
     stats = {"shows": 0, "seasons": 0, "episodes": 0, "pruned": 0}
 
     _sync_shows(db, stub, lib, stats)