refactor(tmdb): ACL pass — push VOs into DTOs, split search per media type

Anti-corruption boundary tightened on the TMDB adapter:

* TmdbMovieInfo / TmdbShowInfo now carry domain VOs (TmdbId, ImdbId,
  MovieTitle, ReleaseYear, ShowStatus) instead of raw scalars —
  validation happens at the boundary, not three layers later.
* ShowStatus enum added (domain/tv_shows/value_objects) with a
  from_tmdb() mapper that falls back to UNKNOWN + logs a warning on
  unrecognized values. TVShow.status is now ShowStatus, not str.
* MovieTitle cap raised from 100 to 150 chars.
* MediaResult / ExternalIds dropped. Replaced by per-media search
  DTOs: TmdbMovieSearchResult and TmdbShowSearchResult. Neither
  carries imdb_id — search no longer enriches with external_ids
  (callers needing imdb_id follow up with get_movie_info /
  get_tv_show_info on the chosen tmdb_id).
* TMDBClient: search_multi / search_media / _parse_result removed.
  search_movies (/search/movie) and search_shows (/search/tv) added,
  each parsing hits into VO-typed DTOs.
* SearchMovieUseCase returns a list of MovieHit (flattened to
  primitives for the agent). New symmetric SearchShowUseCase +
  ShowHit / SearchShowResponse DTOs.
* agent/tools/api.py: find_media_imdb_id → search_movies +
  search_shows wrappers.
* FileEntry moved from domain/shared/ports/filesystem_scanner.py to
  domain/shared/file_entry.py (it's a DTO, not a Protocol); size_kb
  (float) → size (int bytes). Scanner and SubtitleIdentifier
  updated.

Tests: 79/79 pass on tests/infrastructure/api/ +
tests/application/test_search_movie.py +
tests/application/test_search_show.py.

tests/domain/test_subtitle_identifier.py

@@ -22,7 +22,7 @@ from unittest.mock import patch
 
 import pytest
 
-from alfred.domain.shared.ports import FileEntry
+from alfred.domain.shared import FileEntry
 from alfred.domain.subtitles.entities import SubtitleScanResult
 from alfred.domain.subtitles.services.identifier import (
     SubtitleIdentifier,
@@ -48,7 +48,7 @@ def _file_entry(path) -> FileEntry:
         path=path,
         is_file=path.is_file(),
         is_dir=path.is_dir(),
-        size_kb=(path.stat().st_size / 1024) if path.is_file() else None,
+        size=path.stat().st_size if path.is_file() else None,
     )