Add featured Dark House track with default landing ambient playback

Wire featured-dark-house-2025.mp3 as the default ambient source, enable BGM for first-time visitors, and attempt autoplay on Command Deck with gesture-unlock fallback. The ~57MB MP3 stays gitignored; copy instructions are in public/audio/.gitkeep.

server/web/src/audio/ambientMusic.test.ts

@@ -17,11 +17,16 @@ describe('ambientMusic prefs', () => {
     localStorage.clear();
   });
 
-  it('defaults music off and volume ~0.22', () => {
-    expect(loadBgmEnabled()).toBe(false);
+  it('defaults music on for first visit and volume ~0.22', () => {
+    expect(loadBgmEnabled()).toBe(true);
     expect(loadBgmVolume()).toBeCloseTo(0.22);
   });
 
+  it('respects explicit opt-out', () => {
+    localStorage.setItem(BGM_STORAGE_KEY, '0');
+    expect(loadBgmEnabled()).toBe(false);
+  });
+
   it('persists enabled flag', () => {
     const p = new AmbientMusicPlayer();
     p.setEnabled(true);
@@ -38,8 +43,8 @@ describe('ambientMusic prefs', () => {
     expect(localStorage.getItem(BGM_VOLUME_KEY)).toBe('0');
   });
 
-  it('points at public audio path', () => {
-    expect(AMBIENT_MUSIC_SRC).toBe('/audio/ambient.mp3');
+  it('points at featured public audio path', () => {
+    expect(AMBIENT_MUSIC_SRC).toBe('/audio/featured-dark-house-2025.mp3');
   });
 
   it('ducks effective volume 30% while modal registered', () => {

server/web/src/audio/ambientMusic.ts

@@ -1,11 +1,14 @@
 /**
- * Looping background music — drop your MP3 at public/audio/ambient.mp3
- * (MP3 preferred; OGG/WAV also work if you update AMBIENT_MUSIC_SRC).
+ * Looping background music — featured track at public/audio/featured-dark-house-2025.mp3
+ * (copy from repo music/; legacy ambient.mp3 still valid if you change AMBIENT_MUSIC_SRC).
  */
 export const BGM_STORAGE_KEY = 'aetherforge-bgm';
 export const BGM_VOLUME_KEY = 'aetherforge-bgm-volume';
-/** Served from Vite public/ — place ambient.mp3 here before enabling in Settings. */
-export const AMBIENT_MUSIC_SRC = '/audio/ambient.mp3';
+/** Featured Command Deck landing track (gitignored when >15MB — copy locally from music/). */
+export const FEATURED_MUSIC_SRC = '/audio/featured-dark-house-2025.mp3';
+export const FEATURED_MUSIC_TITLE = 'Dark House 2025';
+/** Default looping source for the global ambient player. */
+export const AMBIENT_MUSIC_SRC = FEATURED_MUSIC_SRC;
 
 /** Route → playback multiplier (0–1). User volume × intensity = effective output. */
 export const PAGE_AMBIENT_INTENSITY: Record<string, number> = {
@@ -40,9 +43,10 @@ export function resolvePageAmbientIntensity(pathname: string): number {
 export function loadBgmEnabled(): boolean {
   try {
     const v = localStorage.getItem(BGM_STORAGE_KEY);
+    if (v === null) return true;
     return v === '1';
   } catch {
-    return false;
+    return true;
   }
 }