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_titles.py

@@ -1,4 +1,5 @@
 """normalize_title: de-shout / de-clutter video titles without mangling non-English text."""
+
 from concurrent.futures import ThreadPoolExecutor
 from concurrent.futures import TimeoutError as FuturesTimeout
 
@@ -51,7 +52,9 @@ def test_midstring_hashtags_dont_hang_and_are_kept_redos_regression():
     try:
         out = fut.result(timeout=5) or ""
     except FuturesTimeout:
-        pytest.fail("normalize_title did not return within 5s — catastrophic backtracking regressed")
+        pytest.fail(
+            "normalize_title did not return within 5s — catastrophic backtracking regressed"
+        )
     finally:
         ex.shutdown(wait=False)  # never join a (hypothetically) wedged thread
     assert "#foryoupage" in out and "#reel" in out  # mid-string hashtags preserved (not trailing)