feat(search): personalize suggestions by listening history (M6)

Suggest fetches three times as many candidates and reranks them in the API:
what the user plays, finishes and likes moves up a few positions and what they
dislike moves down, with Meilisearch relevance still the base order.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

services/api/cmd/api/main.go

@@ -170,7 +170,7 @@ func newApp(ctx context.Context, cfg config.API, pool *pgxpool.Pool, rdb *redis.
 		Auth:        auth.NewHandler(authSvc, cfg.CookieSecure),
 		AuthService: authSvc,
 		Library:     library.NewHandler(libSvc, libStore, dto, covers, cfg.XAccel),
-		Search:      search.NewHandler(meili, libStore, indexer, dto, log),
+		Search:      search.NewHandler(meili, libStore, indexer, search.NewAffinity(pool), dto, log),
 		Playback:    pb,
 		Wave: wave.NewHandler(pool, &wave.Recommender{URL: cfg.RecommenderURL, Token: cfg.InternalToken,
 			Client: &http.Client{}}, libStore, func() library.DTO { return dto }, log),