test(fixtures): seed PATH OF PAIN bucket with 10 worst-case fixtures

10 pathological release names mined from the real downloads folder.
Each fixture locks in the current parse_release output (including
its silent losses and false positives) so future parser improvements
are intentional, not silent drift.

Cases:
- Khruangbin yt-dlp slug (UTF-8 wide pipe '｜', YT ID as group)
- Deutschland 83-86-89 franchise box (group=S03 misdetection)
- Chérie Le BéBé (accented chars preserved, VFF language)
- Jimmy Carr 8-word stand-up special title
- [ OxTorrent.vc ] prefix + XviD codec (site_tag prefix)
- Prodiges S12E01 with episode title + air-date silently lost
- The Prodigy: apostrophe + Blu-ray dash + 1080i + multi-word audio
  = full AI-path degeneration (everything UNKNOWN)
- Sleaford Mods yt-dlp slug (YT ID glued to year)
- Super Mario Bros [FR-EN] (bilingual tag mistaken for group)
- Gilmore Girls Complete S01-S07 (the well-behaved exception:
  COMPLETE token correctly drives tv_complete + REPACK + 10bit)

Also adds shitty + path_of_pain to the per-bucket sanity assertion.

Suite: 1020 passed, 8 skipped.

tests/domain/test_release_fixtures.py

@@ -52,3 +52,5 @@ def test_at_least_one_fixture_per_bucket() -> None:
     """Each bucket should hold at least one case once populated."""
     buckets = {f.name.split("/")[0] for f in FIXTURES}
     assert "easy" in buckets, "EASY bucket must have at least one fixture"
+    assert "shitty" in buckets, "SHITTY bucket must have at least one fixture"
+    assert "path_of_pain" in buckets, "PATH_OF_PAIN bucket must have at least one fixture"