Search Deezer and MusicBrainz together; add preview clips

Search
- Albums and songs search Deezer and MusicBrainz at once and merge the
  results: duplicates keep the Deezer copy, best word matches first.
  Deezer's search misses albums it carries (Death Magnetic) and most game
  soundtracks; MusicBrainz finds them
- MusicBrainz secondary types are shown ("Soundtrack", "Live")
- Settings: Deezer + MusicBrainz (default), Deezer only, MusicBrainz only
- Search results show which service they came from

Previews
- Songs and albums get a play button (cards, rows, detail view, editor,
  and Deezer search results) for a 30-second Deezer clip; albums play
  their most popular track
- Clips are looked up fresh (Deezer URLs expire), cached 10 minutes, and
  streamed through Canon with Range support; hidden lists stay private
- Entries from MusicBrainz or added by hand are matched to Deezer on save
  so they can preview too
- "Play previews" toggle in Settings → Profile

Tests cover merging and title/artist matching; `-tags live` runs checks
against the real services.

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

internal/server/api.go

@@ -199,6 +199,7 @@ func (s *Server) apiAddItem(w http.ResponseWriter, r *http.Request) {
 			it.Image, it.ImageSource = name, res.ImageURL
 		}
 	}
+	s.matchDeezer(ctx, list.Category, &it)
 	saved, err := s.store.AddItem(ctx, it, in.Rank)
 	if err != nil {
 		s.releaseImage(ctx, it.Image)
@@ -212,7 +213,7 @@ func (s *Server) apiAddItem(w http.ResponseWriter, r *http.Request) {
 // and the search result is used as-is.
 func (s *Server) fillDetails(ctx context.Context, category string, res providers.Result) providers.Result {
 	p, err := s.providers.For(ctx, category)
-	if err != nil || p.Name() != res.Provider {
+	if err != nil {
 		return res
 	}
 	d, ok := p.(providers.Detailer)
@@ -283,6 +284,11 @@ func (s *Server) apiUpdateItem(w http.ResponseWriter, r *http.Request) {
 		}
 		it.Image, it.ImageSource = name, url
 	}
+	if it.Title != cur.Title || it.Subtitle != cur.Subtitle || it.Extra["deezer"] == "" {
+		if l, err := s.store.ListByID(ctx, it.ListID); err == nil {
+			s.matchDeezer(ctx, l.Category, &it)
+		}
+	}
 	saved, err := s.store.UpdateItem(ctx, it)
 	if err != nil {
 		if it.Image != cur.Image {
@@ -381,7 +387,8 @@ func (s *Server) apiDeleteItem(w http.ResponseWriter, r *http.Request) {
 
 type searchResult struct {
 	providers.Result
-	ExistingRank int `json:"existingRank,omitempty"`
+	ExistingRank int    `json:"existingRank,omitempty"`
+	PreviewRef   string `json:"previewRef,omitempty"` // Deezer id to audition before adding
 }
 
 func (s *Server) apiSearch(w http.ResponseWriter, r *http.Request) {
@@ -409,6 +416,9 @@ func (s *Server) apiSearch(w http.ResponseWriter, r *http.Request) {
 	out := make([]searchResult, 0, len(results))
 	for _, res := range results {
 		sr := searchResult{Result: res}
+		if res.Provider == "deezer" && hasPreviews(category) {
+			sr.PreviewRef = res.ProviderID
+		}
 		if listID > 0 {
 			if it, err := s.store.FindItemByProvider(ctx, listID, res.Provider, res.ProviderID); err == nil {
 				sr.ExistingRank = it.Rank
@@ -478,7 +488,8 @@ func (s *Server) apiSettings(w http.ResponseWriter, r *http.Request) {
 		"customCss":      set[store.SettingCustomCSS],
 		"previewCount":   site.PreviewCount,
 		"showNotes":      site.ShowNotes,
-		"musicProvider":  orDefault(set[store.SettingMusicProvider], "deezer"),
+		"showPreviews":   site.ShowPreviews,
+		"musicProvider":  orDefault(set[store.SettingMusicProvider], "both"),
 		"tvProvider":     orDefault(set[store.SettingTVProvider], "tvdb"),
 		"secrets":        secrets,
 		"themes":         Themes,
@@ -538,7 +549,7 @@ func (s *Server) apiUpdateSettings(w http.ResponseWriter, r *http.Request) {
 		s.writeErr(w, store.ValidationError{Msg: "Unknown theme"})
 		return
 	}
-	if v, ok := out[store.SettingMusicProvider]; ok && v != "deezer" && v != "musicbrainz" {
+	if v, ok := out[store.SettingMusicProvider]; ok && v != "both" && v != "deezer" && v != "musicbrainz" {
 		s.writeErr(w, store.ValidationError{Msg: "Unknown music provider"})
 		return
 	}
@@ -554,6 +565,14 @@ func (s *Server) apiUpdateSettings(w http.ResponseWriter, r *http.Request) {
 		}
 		out[store.SettingPreviewCount] = strconv.Itoa(int(n))
 	}
+	if v, ok := in["showPreviews"]; ok {
+		b, ok := v.(bool)
+		if !ok {
+			s.writeErr(w, store.ValidationError{Msg: "showPreviews must be true or false"})
+			return
+		}
+		out[store.SettingShowPreviews] = strconv.FormatBool(b)
+	}
 	if v, ok := in["showNotes"]; ok {
 		b, ok := v.(bool)
 		if !ok {