feat(search): viewer progress + completed badges; dropdown to templ

Search results now show where you are in a book: a completed check at
the 0.999 threshold (same cut as the filter status arms), a partial
progress bar along the cover while mid-read, nothing when you never
opened it. Rendered in BookCard (any grid whose adapter loads viewer
progress) and in the header-search dropdown rows.

The progress rides a LEFT JOIN reading_progress on the SAME user_id
param SearchMediaItemsUnified already binds for library visibility —
one requester param, no new wire inputs, row-neutral join (the table
is UNIQUE per media_item+user). SearchMediaItemsUnifiedRow and BookInfo
gain the keys additively (viewer_percentage null when unknown,
library_name empty on feeds that don't load it); contract_pins.md
carries the changelog entry and the pin tests widen in lockstep.

The header dropdown itself migrates off the innerHTML string renderer
in search.ts (a rendering-ownership violation: a templ twin existed via
the HX-Request branch). The input now hx-gets layout=dropdown and swaps
the new templ SearchResults partial — titles/authors highlighted
server-side (escape-first, safe by construction), rows with the same
progress overlays — while a slim Alpine component owns only
client-local state (min-length gating, open/close, keyboard selection,
htmx lifecycle). web/src/rendering-allowlist.txt drops the search.ts
baseline to zero accordingly.

Integration test pins the per-user join (fresh user sees 1.0/0.42/null
on the fixture; the shared admin sees null everywhere — read-only) and
the dropdown partial's overlays/count/row count.

web/src/types/api.d.ts

@@ -9,7 +9,8 @@
 // Source: internal/database/queries.sql.go:6123-6170 SearchMediaItemsRow
 // Endpoint: internal/handlers/media.go:SearchMediaItems()
 // Note: internal/handlers/search.go has an unused MediaItemSummary - ignore it
-// Used in: search.ts
+// Used in: search.ts (dropdown content is templ-rendered since the
+// 2026-10-27 search-progress batch; this type documents the JSON API)
 interface MediaItemSummary {
   id: string;
   library_id: string;
@@ -57,6 +58,8 @@ interface MediaItemSummary {
   hash_confidence?: string;
   library_name: string;
   library_type_name: string;
+  /** Requesting user's progress 0..1; null when never opened (2026-10-27). */
+  viewer_percentage?: number | null;
 
   // NEW: Reading direction fields for manga/comics
   manga_type?: "unknown" | "no" | "yes" | "yes_and_right_to_left";