feat(plex): expanded metadata filters, clickable info page, image disk cache

Backend (migration 0045_plex_filter_meta): plex_items gains rating (audienceRating
~IMDb), content_rating, studio, originally_available_at, and GIN-indexed genres /
directors / cast_names — all mirrored from the cheap section listing (no per-item API
calls; they also seed a future watch-habit recommender). /browse gains genre / content-
rating / year / rating / duration / added-within / director / actor / studio filters
(@> containment, GIN) + sort by year|rating|duration|release; new /facets endpoint
returns available genres+ratings (with counts) and the year/rating/duration bounds. A
thin on-disk image cache (.plex-img-cache) serves posters/art/cast photos from local
disk after first fetch (~7-14x faster repeat loads).

Frontend: PlexSidebar grows the full filter set (facet-driven genre/age chips, rating
steps, year range inputs, duration buckets, added-within, active people/studio chips,
clear-all); filters persist per-account as one JSON blob. PlexInfo metadata (year,
genre, director, cast, studio, IMDb score) is clickable → sets the matching filter and
returns to the filtered grid (page variant only; the in-player overlay stays read-only
so a stray click can't stop playback). i18n en/hu/de.

backend/app/plex/sync.py

@@ -56,6 +56,29 @@ def _epoch(v) -> datetime | None:
         return None
 
 
+def _date(v):
+    """Parse a Plex 'YYYY-MM-DD' string (originallyAvailableAt) → date, or None."""
+    try:
+        return datetime.strptime(v, "%Y-%m-%d").date() if v else None
+    except (TypeError, ValueError):
+        return None
+
+
+def _tags(meta: dict, key: str, limit: int | None = None) -> list | None:
+    """The .tag values of a Plex child-tag array (Genre/Director/Role) present in the listing."""
+    vals = [t.get("tag") for t in (meta.get(key) or []) if t.get("tag")]
+    if limit:
+        vals = vals[:limit]
+    return vals or None
+
+
+def _rating(meta: dict) -> float | None:
+    try:
+        return float(meta.get("audienceRating") or meta.get("rating"))
+    except (TypeError, ValueError):
+        return None
+
+
 def _media_facts(meta: dict) -> dict:
     media = meta.get("Media") or []
     if not media:
@@ -152,6 +175,14 @@ def _apply_item(row: PlexItem, lib_id: int, kind: str, meta: dict) -> None:
     row.thumb_key = meta.get("thumb")
     row.art_key = meta.get("art") or meta.get("grandparentArt")
     row.added_at = _epoch(meta.get("addedAt"))
+    # Filterable / orderable extras — all present in the cheap section listing.
+    row.rating = _rating(meta)
+    row.content_rating = (meta.get("contentRating") or None)
+    row.studio = (meta.get("studio") or None) and str(meta.get("studio"))[:255]
+    row.originally_available_at = _date(meta.get("originallyAvailableAt"))
+    row.genres = _tags(meta, "Genre")
+    row.directors = _tags(meta, "Director")
+    row.cast_names = _tags(meta, "Role", limit=20)
     mf = _media_facts(meta)
     row.file_path = mf.get("file_path")
     row.part_key = mf.get("part_key")