dev: umfangreiches Refactoring, Trakt-Integration und Code-Review-Fixes (0.1.69-dev)

Core & Architektur:
- Neues Verzeichnis addon/core/ mit router.py, trakt.py, metadata.py,
  gui.py, playstate.py, plugin_manager.py, updater.py
- Tests-Verzeichnis hinzugefügt (24 Tests, pytest + Coverage)

Trakt-Integration:
- OAuth Device Flow, Scrobbling, Watchlist, History, Calendar
- Upcoming Episodes, Weiterschauen (Continue Watching)
- Watched-Status in Episodenlisten
- _trakt_find_in_plugins() mit 5-Min-Cache

Serienstream-Suche:
- API-Ergebnisse werden immer mit Katalog-Cache ergänzt (serverseitiges 10-Treffer-Limit)
- Katalog-Cache wird beim Addon-Start im Daemon-Thread vorgewärmt
- Notification nach Cache-Load via xbmc.executebuiltin() (thread-sicher)

Bugfixes (Code-Review):
- Race Condition auf _TRAKT_WATCHED_CACHE: _TRAKT_WATCHED_CACHE_LOCK hinzugefügt
- GUI-Dialog aus Daemon-Thread: xbmcgui -> xbmc.executebuiltin()
- ValueError in Trakt-Watchlist-Routen abgesichert
- Token expires_at==0 Check korrigiert
- get_setting_bool() Kontrollfluss in gui.py bereinigt
- topstreamfilm_plugin: try-finally um xbmcvfs.File.close()

Cleanup:
- default.py.bak und refactor_router.py entfernt
- .gitignore: /tests/ Eintrag entfernt
- Type-Hints vereinheitlicht (Dict/List/Tuple -> dict/list/tuple)

addon/tmdb.py

@@ -557,3 +557,51 @@ def lookup_tv_season(
             continue
         result[ep_number] = TmdbEpisodeMeta(plot=plot, thumb=thumb, runtime_minutes=runtime_minutes)
     return result or None
+
+
+# ---------------------------------------------------------------------------
+# External IDs (IMDb, TVDb) – für Trakt-Integration
+# ---------------------------------------------------------------------------
+
+@dataclass(frozen=True)
+class TmdbExternalIds:
+    imdb_id: str   # z.B. "tt1234567"
+    tvdb_id: int   # TheTVDB-ID
+
+
+def fetch_external_ids(
+    *,
+    kind: str,
+    tmdb_id: int,
+    api_key: str,
+    timeout: int = 15,
+    log: Callable[[str], None] | None = None,
+    log_responses: bool = False,
+) -> Optional[TmdbExternalIds]:
+    """Ruft IMDb-ID und TVDb-ID via /movie/{id}/external_ids oder /tv/{id}/external_ids ab."""
+    if requests is None or not tmdb_id:
+        return None
+    api_key = (api_key or "").strip()
+    if not api_key:
+        return None
+    kind = (kind or "").strip()
+    if kind not in ("movie", "tv"):
+        return None
+    params = {"api_key": api_key}
+    url = f"{TMDB_API_BASE}/{kind}/{tmdb_id}/external_ids?{urlencode(params)}"
+    status, payload, body_text = _tmdb_get_json(
+        url=url, timeout=timeout, log=log, log_responses=log_responses,
+    )
+    if callable(log):
+        log(f"TMDB RESPONSE /{kind}/{{id}}/external_ids status={status}")
+    if status != 200 or not isinstance(payload, dict):
+        return None
+    imdb_id = (payload.get("imdb_id") or "").strip()
+    tvdb_id = 0
+    try:
+        tvdb_id = int(payload.get("tvdb_id") or 0)
+    except (ValueError, TypeError):
+        tvdb_id = 0
+    if not imdb_id and not tvdb_id:
+        return None
+    return TmdbExternalIds(imdb_id=imdb_id, tvdb_id=tvdb_id)