feat(web): book reviews — markdown, sibling of ratings, full API + page surface

media_reviews table mirrors media_ratings' shape (unique per user+item,
cascade deletes, updated_at for LWW) but standalone: a review without a
rating must work. Body is RAW MARKDOWN — storage and every payload carry
the source; rendering happens only at display sites (same doctrine as
notes, same sanitization pipeline: markdown-it + DOMPurify).

API: GET/PUT/DELETE /api/media-items/:id/review (PUT upserts; an empty
body deletes — clearing via an editor is a delete, not an empty row).
Book-detail page payload now carries the review beside the rating.

Page: the review renders above the synopsis as a scrolling card (same
max-height box as the summary), hydrated client-side through
renderNoteHtml; 'Write review'/'Edit review' sits next to the rating
stars and opens a raw-markdown editor dialog (save / delete / cancel).

sqlc regenerated; schema applied to the dev DB. Live-verified: upsert,
get, empty-delete, page markup, and the app round-trip against the dev
server.

internal/database/queries/queries.sql

@@ -550,6 +550,21 @@ RETURNING *;
 -- name: DeleteMediaRating :exec
 DELETE FROM media_ratings WHERE media_item_id = $1 AND user_id = $2;
 
+-- name: UpsertMediaReview :one
+INSERT INTO media_reviews (media_item_id, user_id, review)
+VALUES ($1, $2, $3)
+ON CONFLICT (media_item_id, user_id)
+DO UPDATE SET
+    review = EXCLUDED.review,
+    updated_at = NOW()
+RETURNING *;
+
+-- name: GetMediaReview :one
+SELECT * FROM media_reviews WHERE media_item_id = $1 AND user_id = $2;
+
+-- name: DeleteMediaReview :exec
+DELETE FROM media_reviews WHERE media_item_id = $1 AND user_id = $2;
+
 -- Search Media Items queries
 -- name: SearchMediaItems :many
 SELECT mi.*, l.name as library_name, lt.name as library_type_name