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.

templates/collection_modal.templ

@@ -72,6 +72,18 @@ templ CollectionModal(collection CollectionData) {
 							<button type="button" @click="selectColor('purple')" data-color="purple" class="w-8 h-8 rounded-full color-option bg-purple-500 hover:ring-2 hover:ring-offset-2 hover:ring-offset-transparent hover:ring-purple-400" aria-label="Purple"></button>
 						</div>
 						<input type="hidden" name="color" id="collection-color" value={ collection.Color }/>
+						<div class="mb-4 space-y-2">
+							<label class="flex items-center gap-2 text-sm" style="color: var(--text-primary);">
+								<input type="hidden" name="hide_finished" value="false"/>
+								<input type="checkbox" name="hide_finished" value="true" checked={ collection.HideFinished } class="h-4 w-4 accent-current"/>
+								<span>Hide finished books (reading-queue mode)</span>
+							</label>
+							<label class="flex items-center gap-2 text-sm" style="color: var(--text-primary);">
+								<input type="hidden" name="show_up_next" value="false"/>
+								<input type="checkbox" name="show_up_next" value="true" checked={ collection.ShowUpNext } class="h-4 w-4 accent-current"/>
+								<span>Show Up Next strip</span>
+							</label>
+						</div>
 					</div>
 					<div class="flex justify-end space-x-3">
 						<button type="button" @click="closeCollectionModal()" class="btn btn-secondary">Cancel</button>