MusicStudio: Suno/MusicGen 듀얼 프로바이더 UI 추가

- Provider 선택 바 (Suno 🎙️ / MusicGen 🤖)
- Suno 전용: 보컬/인스트루멘탈 토글, 가사 입력, AI 가사 생성
- 라이브러리·결과 카드에 provider 뱃지 표시
- TrackResult에 가사 접기/펼치기 추가
- api.js: getMusicProviders, generateMusicLyrics 함수 추가

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/api.js

@@ -247,20 +247,33 @@ export function deleteSellHistory(id) {
 }
 
 // ── AI 음악 생성 API ──────────────────────────────────────────────────────────
-// POST /api/music/generate  body: { genre, moods, instruments, duration_sec, bpm, key, scale, prompt }
-// → { task_id: string }
+
+// GET /api/music/providers → { providers: [{ id, name, description, features }] }
+export function getMusicProviders() {
+  return apiGet('/api/music/providers');
+}
+
+// POST /api/music/generate
+// body: { provider, genre, moods, instruments, duration_sec, bpm, key, scale, prompt, lyrics, instrumental }
+// → { task_id: string, provider: string }
 export function generateMusic(payload) {
   return apiPost('/api/music/generate', payload);
 }
 
 // GET /api/music/status/:task_id
-// → { status: "queued"|"processing"|"succeeded"|"failed", progress: 0~100, message, audio_url?, error? }
+// → { status, progress, message, audio_url?, error?, provider?, track? }
 export function getMusicStatus(taskId) {
   return apiGet(`/api/music/status/${encodeURIComponent(taskId)}`);
 }
 
+// POST /api/music/lyrics  body: { prompt }
+// → { id, status, text } (Suno 가사 생성)
+export function generateMusicLyrics(prompt) {
+  return apiPost('/api/music/lyrics', { prompt });
+}
+
 // GET /api/music/library
-// → { tracks: [{ id, title, genre, moods, instruments, duration_id, bpm, key, scale, audio_url, created_at }] }
+// → { tracks: [{ id, title, genre, ..., provider, lyrics, image_url, suno_id }] }
 export function getMusicLibrary() {
   return apiGet('/api/music/library');
 }