feat(facets): facet registry, Batch A server params, genre model v2, facets endpoint

Phase 1 + backend of Phase 2 of the faceted-navigation plan. One
declarative facet registry (services/facet_registry.go) drives the
bookshelf filter system; a drift-guard unit test reflects over the
generated SearchMediaItemsUnifiedParams so a registry entry and its
sqlc.narg block can never disagree silently.

- Nine new filter params on SearchMediaItemsUnified: story_arc,
  imprint, edition (scalar-fuzzy), age_rating, format_group,
  manga_type, reading_direction (exact), explicit, abridged
  (presence-bound bools). Comma = OR-within multi-select on every
  text facet; AND-across-facets unchanged.
- Genre model v2 (user rule: a subgenre is not a genre, it's a tag):
  genre_lexicon.go rebuilt as shelf set + subgenre->shelf map;
  pickSmartGenre picks direct shelf > mapped subgenre > Fiction floor
  > empty (unknown-only stays tags-only). Type-words (Manga, Comics,
  Graphic Novel) join the demote list. Both 'adventure' and 'action &
  adventure' are shelves — provider data uses both and the verified
  traces pin them.
- Language filter UX: comma elements normalize through the ingest
  language map, so display names ('English') match rows stored as ISO
  codes ('en'). The language autocomplete now serves display names.
- NEW GET /api/media-items/facets?facet=X&library_id=... — registry-
  driven value+count listing (14 static per-column queries, family-lens
  join); language values carry display names; bool/range facets 400.
- Family-lens gates: an explicit hidden-library library_id is now a
  403 on the search endpoints (was a silent empty set) — JSON branch
  and HTMX grid partial both.
- handlers.ParseMediaSearchParams is the SINGLE param parser for the
  search JSON endpoint and the HTMX grid partial; the HTML branch
  previously dropped publisher_filter and narrator_filter silently.

Pins: docs/contract_pins.md changelog entries (additive request
params; new facets endpoint). Tests: facet_registry_test.go (shape +
SQL drift guard + library-type union), series_parsing_test.go genre-v2
cases, facets_integration_test.go (param filtering e2e, counts,
language display, 403s) — container runner.

internal/database/querier.go

@@ -164,6 +164,27 @@ type Querier interface {
 	// historically stuff the user id into DeviceID (it only fed a broadcast
 	// label before stats); a capture row must only reference a REAL device.
 	DeviceExistsForUser(ctx context.Context, arg DeviceExistsForUserParams) (bool, error)
+	FacetAgeRatingValues(ctx context.Context, arg FacetAgeRatingValuesParams) ([]FacetAgeRatingValuesRow, error)
+	// Facet-value listings (faceted-navigation Batch C): top values + counts
+	// for the filter panel, one static query per media_items column (same
+	// sqlc-compatibility constraint as the Search*Values autocomplete above).
+	// Visibility: same family-lens join as the search query — a user's
+	// hidden-library rows are absent, and the handler 403s an out-of-set
+	// explicit library_id. Counts are v1 global-per-library (not
+	// recomputed under the other active filters).
+	FacetAuthorsValues(ctx context.Context, arg FacetAuthorsValuesParams) ([]FacetAuthorsValuesRow, error)
+	FacetEditionValues(ctx context.Context, arg FacetEditionValuesParams) ([]FacetEditionValuesRow, error)
+	FacetFormatGroupValues(ctx context.Context, arg FacetFormatGroupValuesParams) ([]FacetFormatGroupValuesRow, error)
+	FacetGenreValues(ctx context.Context, arg FacetGenreValuesParams) ([]FacetGenreValuesRow, error)
+	FacetImprintValues(ctx context.Context, arg FacetImprintValuesParams) ([]FacetImprintValuesRow, error)
+	FacetLanguageValues(ctx context.Context, arg FacetLanguageValuesParams) ([]FacetLanguageValuesRow, error)
+	FacetMangaTypeValues(ctx context.Context, arg FacetMangaTypeValuesParams) ([]FacetMangaTypeValuesRow, error)
+	FacetNarratorsValues(ctx context.Context, arg FacetNarratorsValuesParams) ([]FacetNarratorsValuesRow, error)
+	FacetPublishersValues(ctx context.Context, arg FacetPublishersValuesParams) ([]FacetPublishersValuesRow, error)
+	FacetReadingDirectionValues(ctx context.Context, arg FacetReadingDirectionValuesParams) ([]FacetReadingDirectionValuesRow, error)
+	FacetSeriesValues(ctx context.Context, arg FacetSeriesValuesParams) ([]FacetSeriesValuesRow, error)
+	FacetStoryArcValues(ctx context.Context, arg FacetStoryArcValuesParams) ([]FacetStoryArcValuesRow, error)
+	FacetTagsValues(ctx context.Context, arg FacetTagsValuesParams) ([]FacetTagsValuesRow, error)
 	// Find content-duplicate groups (same library + SHA-256, more than one row)
 	FindHashConflictGroups(ctx context.Context) ([]FindHashConflictGroupsRow, error)
 	GenerateKoboEntitlementId(ctx context.Context) (interface{}, error)