refactor(domain): Phase 3 — TVShow/Movie aggregates become TMDB-only

Filesystem-side concerns (file paths, tracks, quality, mode, added_at)
move to the releases/ domain added in Phase 1; the TMDB aggregates now
carry only identity + TMDB catalog facts.

Domain entities:
- TVShow: tmdb_id: TmdbId required (primary key), imdb_id: ImdbId | None
  optional, status: str = "unknown" added.
- Season: episode_count: int = 0 added (TMDB-cached); audio_tracks,
  subtitle_tracks, mode property removed.
- Episode: slimmed to identity + title. file_path/file_size/tracks
  removed. No longer inherits MediaWithTracks.
- Movie: tmdb_id required, imdb_id optional. file_path/file_size/quality/
  added_at/audio_tracks/subtitle_tracks removed. get_filename() now
  returns "Title.Year" — quality moves to MovieRelease.

Builders:
- TVShowBuilder requires tmdb_id: TmdbId; imdb_id/status optional.
- SeasonBuilder.set_episode_count(int) replaces set_audio_tracks /
  set_subtitle_tracks.

No-coercion contract: TVShow(tmdb_id=1396) raises — callers pass
TmdbId(1396). No ergonomic shim per the no-shims rule.

Cascade fixes:
- MediaOrganizer test fixtures updated to new Movie/TVShow shapes.
- Movie.get_filename() re-added (without Quality) so MediaOrganizer
  keeps working until Phase 4 rewires it through MovieRelease.

Quarantined (deleted in Phase 4 alongside v1 dot_alfred):
- tests/application/library/test_rescan.py — module-level skip.
- tests/infrastructure/persistence/dot_alfred/test_repository.py —
  module-level skip.
- tests/infrastructure/persistence/dot_alfred/test_serializer.py —
  module-level skip.

Suite: 1216 passed, 11 skipped (8 pre-existing + 3 Phase 3
quarantines), 4 xfailed. CHANGELOG updated under [Unreleased].

tests/infrastructure/persistence/dot_alfred/test_serializer.py

@@ -21,7 +21,15 @@ from __future__ import annotations
 import pytest
 import yaml
 
-from alfred.domain.shared.value_objects import ImdbId
+# Phase 3 (refactor/dot-alfred-v2): v1 serializer is intentionally
+# left in tree as a frozen reference until Phase 4 deletes both v1
+# and this test module in one swing.
+pytest.skip(
+    "v1 dot_alfred serializer — replaced in Phase 4",
+    allow_module_level=True,
+)
+
+from alfred.domain.shared.value_objects import ImdbId  # noqa: E402
 from alfred.domain.tv_shows.value_objects import EpisodeNumber, SeasonNumber
 from alfred.infrastructure.persistence.dot_alfred import (
     EpisodeSidecar,