fix(plex): summaries and taglines are stored as plain text

A Plex agent can hand a summary over as HTML (<p> paragraphs, &aacute;
entities); the info page and the hover card showed the tags. One cleaner,
app/plex/plaintext.py, now runs on every summary and tagline the sync, the
Hungarian overlay and the rich-detail fetch store, and migration 0101 cleans
the rows written before through the same function. Paragraph breaks survive
as newlines, which the info page and the hover card now keep.

backend/app/plex/sync.py

@@ -26,6 +26,7 @@ from app.plex import detail, overlay, people
 from app.plex.client import PlexClient, PlexError, PlexNotConfigured
 from app.plex.genres import hu_genres
 from app.plex.lookups import by_rating_key
+from app.plex.plaintext import plain_text
 
 log = logs.get_logger(__name__)
 # Codecs/containers a browser can play in a native <video> without any transcoding.
@@ -468,7 +469,7 @@ def _apply_item(row: PlexItem, lib_id: int, kind: str, meta: dict) -> None:
     # carries none (a server ignoring includeGuids mustn't wipe the overlay's only match key).
     row.guid = _canonical_guid(meta) or row.guid
     row.title = (meta.get("title") or "").strip() or "Untitled"
-    row.summary = meta.get("summary")
+    row.summary = plain_text(meta.get("summary"))
     row.year = meta.get("year")
     row.duration_s = _dur_s(meta)
     row.thumb_key = meta.get("thumb")
@@ -576,7 +577,7 @@ def _sync_shows(db: Session, plex: PlexClient, lib: PlexLibrary, stats: dict) ->
             _canonical_guid(meta) or sh.guid
         )  # EN<->HU pairing key; keep prior if listing has none
         sh.title = (meta.get("title") or "").strip() or "Untitled"
-        sh.summary = meta.get("summary")
+        sh.summary = plain_text(meta.get("summary"))
         sh.year = meta.get("year")
         sh.thumb_key = meta.get("thumb")
         sh.art_key = meta.get("art")
@@ -659,7 +660,7 @@ def _upsert_collection(
         db.add(col)
     col.library_id = lib_id
     col.title = (meta.get("title") or "").strip() or "Untitled"
-    col.summary = meta.get("summary")
+    col.summary = plain_text(meta.get("summary"))
     col.thumb_key = meta.get("thumb")
     col.child_count = meta.get("childCount")
     col.smart = str(meta.get("smart")) == "1"