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.

internal/database/queries/queries.sql

@@ -734,11 +734,17 @@ SELECT
   mi.opf_uuid,
   mi.hash_confidence,
   l.name as library_name,
-  lt.name as library_type_name
+  lt.name as library_type_name,
+  -- Viewer's own progress (search-result badges): NULL when the
+  -- requester never opened the book. Reuses the SAME requester param
+  -- the visibility join binds; UNIQUE(media_item, user) keeps the
+  -- join row-neutral.
+  rp.percentage as viewer_percentage
 FROM media_items mi
 JOIN libraries l ON mi.library_id = l.id
 JOIN library_types lt ON l.library_type_id = lt.id
 LEFT JOIN library_visibility lv ON l.id = lv.library_id AND lv.user_id = sqlc.narg('user_id')
+LEFT JOIN reading_progress rp ON rp.media_item_id = mi.id AND rp.user_id = sqlc.narg('user_id')
 WHERE COALESCE(lv.is_visible, true) = true
   AND mi.archived_at IS NULL
   AND mi.missing_scan_count = 0