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>

web/static/js/admin-settings.js

@@ -77,6 +77,7 @@ function profileSection() {
   const tagline = h("input", { maxlength: 300, value: settings.tagline, placeholder: "A line about you or your taste" });
   const preview = h("input", { type: "number", min: 0, max: 50, value: settings.previewCount, style: { maxWidth: "120px" } });
   const notes = h("input", { type: "checkbox", checked: settings.showNotes });
+  const previews = h("input", { type: "checkbox", checked: settings.showPreviews });
   const save = h("button", { type: "submit", class: "btn btn--primary" }, "Save profile");
 
   const form = h("form", { class: "stack" },
@@ -85,13 +86,14 @@ function profileSection() {
     field("Tagline", tagline),
     field("Entries per list on the home page", preview, "Visitors see the full list on each list's page. 0 shows only the heading."),
     h("label", { class: "check" }, notes, "Show why each entry is ranked where it is"),
+    h("label", { class: "check" }, previews, "Play 30-second previews for songs and albums (from Deezer)"),
     h("div", { class: "settings-actions" }, save),
   );
   form.addEventListener("submit", async (e) => {
     e.preventDefault();
     const ok = await saveSettings({
       ownerName: ownerName.value, siteTitle: siteTitle.value, tagline: tagline.value,
-      previewCount: Number(preview.value), showNotes: notes.checked,
+      previewCount: Number(preview.value), showNotes: notes.checked, showPreviews: previews.checked,
     }, save, "Profile saved");
     if (ok) {
       renderAvatar();
@@ -304,8 +306,8 @@ function integrationsSection() {
     }),
     integration({
       title: "Music · Songs & Albums", iconName: "disc", category: "album",
-      desc: "No key needed. Deezer has the best cover art and fast search; MusicBrainz is fully open data but slower (1 request/second).",
-      extra: [providerChoice("musicProvider", [["deezer", "Deezer (recommended)"], ["musicbrainz", "MusicBrainz + Cover Art Archive"]])],
+      desc: "No key needed. Searching both finds the most: Deezer has the best art and preview clips, and MusicBrainz covers albums Deezer's search misses plus game and film soundtracks.",
+      extra: [providerChoice("musicProvider", [["both", "Deezer + MusicBrainz (recommended)"], ["deezer", "Deezer only"], ["musicbrainz", "MusicBrainz only"]])],
       ready: () => true,
     }),
     integration({