feat(filters+ui): per-element author/publisher filters, playlist toggles, Up Next API, reorder UI, dashboard badges

Phases 4 + 5 of the metadata overhaul (plan §4, §5) plus §3 handler
wiring.

Filters (§4.1): author_filter/publisher_filter now match per-element
against the authors[]/publishers[] arrays — a co-authored book matches
any one of its authors — with comma-joined params acting as
OR-within-facet multi-select (string_to_array + cross unnest). Legacy
single-value params unchanged on the wire; series/genre/language
filters stay on their varchar columns; narrator filter already
per-element.

Collections API (§3.3-3.5): collection detail carries viewer +
hide_finished into the listing query and exposes up_next (visible-
library-enforced reading-queue head); PUT
/api/collections/:id/items/order (owner-only, full-order rewrite);
UpdateCollectionRequest gains hide_finished/show_up_next ([]
string last-value-wins for the hidden-false-sibling checkbox pattern)
merged server-side OVER stored view_settings so imported_from_series
provenance survives edits; EditCollectionModal renders the toggles
from view_settings.

Dashboard (§5.5): sections JSON carries is_playlist/complete
(dashboard.ts is the AGENTS-documented JSON-render exception; first
paint stays templ). Fully-read playlists render '✓ Playlist complete'
instead of an empty rail; imported playlists get a 📖 Playlist badge.

Frontend: book detail shows subtitle + full authors + Explicit badge;
edit modal gains subtitle, comma-separated authors/publishers (client-
split to arrays exactly like narrators), step=any series number,
explicit checkbox; collection book cards get playlist move ↑/↓ buttons
persisting the full order via the reorder endpoint (templ partial
re-render on failure — DOM order is client-local, API order is truth).

AGENTS.md gotcha #3 amended per plan §3.7: user collections are
dashboard sections by default; the show_on_dashboard premise is
retired.

Verified: full affected integration sweep green (pins widened for
up_next/is_playlist/complete — changelog entries in
docs/contract_pins.md); unit suite green; go build + templ + vite
green.

internal/database/queries/queries.sql

@@ -679,14 +679,26 @@ WHERE COALESCE(lv.is_visible, true) = true
   AND mi.missing_scan_count = 0
   AND (sqlc.narg('library_id')::uuid IS NULL
   OR mi.library_id = sqlc.narg('library_id')::uuid)
-  -- Fuzzy author filter
-  AND (sqlc.narg('author_filter') = '' OR word_similarity(sqlc.narg('author_filter'), COALESCE(mi.author, '')) > 0.3)
+  -- Fuzzy author filter — per-element against the authors[] array (A2c
+  -- §4.1): a co-authored book matches ANY one of its authors, and a
+  -- comma-joined param is multi-select (OR within the facet).
+  AND (sqlc.narg('author_filter') = '' OR EXISTS (
+    SELECT 1
+    FROM unnest(string_to_array(sqlc.narg('author_filter'), ',')) AS f
+    JOIN unnest(mi.authors) AS a ON true
+    WHERE word_similarity(f, COALESCE(a, '')) > 0.3
+  ))
   -- Fuzzy series filter
   AND (sqlc.narg('series_filter') = '' OR word_similarity(sqlc.narg('series_filter'), COALESCE(mi.series, '')) > 0.3)
   -- Fuzzy genre filter
   AND (sqlc.narg('genre_filter') = '' OR word_similarity(sqlc.narg('genre_filter'), COALESCE(mi.genre, '')) > 0.3)
-  -- Fuzzy publisher filter
-  AND (sqlc.narg('publisher_filter') = '' OR word_similarity(sqlc.narg('publisher_filter'), COALESCE(mi.publisher, '')) > 0.3)
+  -- Fuzzy publisher filter — per-element against publishers[] (A2c §4.1).
+  AND (sqlc.narg('publisher_filter') = '' OR EXISTS (
+    SELECT 1
+    FROM unnest(string_to_array(sqlc.narg('publisher_filter'), ',')) AS f
+    JOIN unnest(mi.publishers) AS p ON true
+    WHERE word_similarity(f, COALESCE(p, '')) > 0.3
+  ))
   -- Fuzzy language filter
   AND (sqlc.narg('language_filter') = '' OR word_similarity(sqlc.narg('language_filter'), COALESCE(mi.language, '')) > 0.3)
   -- Tags filter (NEW - fuzzy match against tags array)