feat(cache): TMDB image proxy, posters, cache admin API and settings cards

GET /img/tmdb/{size}/{file} ported from MP ImageHelper / fetch_image
(sanitized cache path under DATA_DIR/cache/images, GLOBAL_IMAGE_CACHE
read switch, md5 ETag / 304, day-based cleanup job). Cache module adds
cache.sweep / cache.images_clean jobs and /cache/tmdb, /cache/images
list and clear endpoints. Library list/detail and the search palette
show posters with the neutral placeholder as fallback; metadata settings
get TMDB cache and image cache cards. Runbook docs/runbook/cache.md and
porting notes docs/porting/moviepilot-tmdb-cache.md.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

packages/contracts/src/index.ts

@@ -4,6 +4,7 @@ export * from "./api.ts";
 export * from "./assets.ts";
 export * from "./auth.ts";
 export * from "./browser.ts";
+export * from "./cache.ts";
 export * from "./capabilities-io.ts";
 export * from "./capability.ts";
 export * from "./common.ts";