feat(plex): TV-show metadata sync + series filters (Phase 1 of series view)

Give TV shows the same filterable metadata as movies so the TV grid can be
filtered/sorted, not just library+sort. Backend: migration 0052 adds
rating/content_rating/studio/originally_available_at/genres/directors/cast_names/
people_text to plex_shows (+ GIN/indexes, people_text folded into search_vector);
_sync_shows populates them cheaply from the show section listing (no per-item
calls). /browse show-branch gains the movie filter set (minus duration) plus an
aggregate per-user watch-state (a show rolls up its episodes: all watched=watched,
any progress=in_progress, none=new) with year/rating/release sorts; /facets returns
show facets. Frontend: PlexSidebar renders the metadata filters + watch-state for TV
libraries (duration stays movie-only); show cards show a watched/in-progress badge.
i18n plex.inProgress (en/hu/de). Needs a Plex re-sync to populate the new columns.

backend/alembic/versions/0052_plex_show_meta.py

@@ -0,0 +1,91 @@
+"""Plex show-level filterable/orderable metadata
+
+Revision ID: 0052_plex_show_meta
+Revises: 0051_plex_link
+Create Date: 2026-07-10
+
+Gives TV shows the same filterable metadata movies already have (0045/0046), mirrored cheaply from
+the Plex show section listing (no per-item calls): rating (audienceRating ~ IMDb), content rating,
+studio/network, first-air date, and GIN-indexed genre / director / cast arrays + a `people_text`
+blob folded into the generated `search_vector` (weight B). This lets the TV grid be filtered and
+sorted like the movie grid. A generated column's expression can't be altered in place, so the
+search_vector is dropped + recreated. All new columns are populated on the next Plex sync.
+"""
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+from sqlalchemy.dialects import postgresql
+
+revision: str = "0052_plex_show_meta"
+down_revision: Union[str, None] = "0051_plex_link"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+_CFG = "public.unaccent_simple"
+_NEW_VECTOR = (
+    f"setweight(to_tsvector('{_CFG}', coalesce(title, '')), 'A') || "
+    f"setweight(to_tsvector('{_CFG}', coalesce(people_text, '')), 'B') || "
+    f"setweight(to_tsvector('{_CFG}', left(coalesce(summary, ''), 1000)), 'C')"
+)
+_OLD_VECTOR = (
+    f"setweight(to_tsvector('{_CFG}', coalesce(title, '')), 'A') || "
+    f"setweight(to_tsvector('{_CFG}', left(coalesce(summary, ''), 1000)), 'C')"
+)
+
+
+def _rebuild_vector(expr: str) -> None:
+    op.execute("DROP INDEX IF EXISTS ix_plex_shows_search_vector")
+    op.execute("ALTER TABLE plex_shows DROP COLUMN search_vector")
+    op.execute(
+        f"ALTER TABLE plex_shows ADD COLUMN search_vector tsvector "
+        f"GENERATED ALWAYS AS ({expr}) STORED"
+    )
+    op.execute("CREATE INDEX ix_plex_shows_search_vector ON plex_shows USING gin (search_vector)")
+
+
+def upgrade() -> None:
+    op.add_column("plex_shows", sa.Column("rating", sa.Float(), nullable=True))
+    op.add_column("plex_shows", sa.Column("content_rating", sa.String(length=16), nullable=True))
+    op.add_column("plex_shows", sa.Column("studio", sa.String(length=255), nullable=True))
+    op.add_column("plex_shows", sa.Column("originally_available_at", sa.Date(), nullable=True))
+    op.add_column("plex_shows", sa.Column("genres", postgresql.JSONB(), nullable=True))
+    op.add_column("plex_shows", sa.Column("directors", postgresql.JSONB(), nullable=True))
+    op.add_column("plex_shows", sa.Column("cast_names", postgresql.JSONB(), nullable=True))
+    op.add_column("plex_shows", sa.Column("people_text", sa.Text(), nullable=True))
+
+    op.create_index("ix_plex_shows_rating", "plex_shows", ["rating"])
+    op.create_index("ix_plex_shows_content_rating", "plex_shows", ["content_rating"])
+    op.create_index("ix_plex_shows_studio", "plex_shows", ["studio"])
+    op.create_index("ix_plex_shows_originally_available_at", "plex_shows", ["originally_available_at"])
+    op.create_index("ix_plex_shows_genres_gin", "plex_shows", ["genres"], postgresql_using="gin")
+    op.create_index("ix_plex_shows_directors_gin", "plex_shows", ["directors"], postgresql_using="gin")
+    op.create_index("ix_plex_shows_cast_gin", "plex_shows", ["cast_names"], postgresql_using="gin")
+    # NB: ix_plex_shows_collections_gin already exists (created with collections in 0047).
+
+    _rebuild_vector(_NEW_VECTOR)
+
+
+def downgrade() -> None:
+    _rebuild_vector(_OLD_VECTOR)
+    for ix in (
+        "ix_plex_shows_cast_gin",
+        "ix_plex_shows_directors_gin",
+        "ix_plex_shows_genres_gin",
+        "ix_plex_shows_originally_available_at",
+        "ix_plex_shows_studio",
+        "ix_plex_shows_content_rating",
+        "ix_plex_shows_rating",
+    ):
+        op.drop_index(ix, table_name="plex_shows")
+    for col in (
+        "people_text",
+        "cast_names",
+        "directors",
+        "genres",
+        "originally_available_at",
+        "studio",
+        "content_rating",
+        "rating",
+    ):
+        op.drop_column("plex_shows", col)