feat(music-lab): Phase 3 UI — RemixTab + 뮤직비디오 생성

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

src/api.js

@@ -363,6 +363,33 @@ export function generateStyleBoost(content) {
   return apiPost('/api/music/style-boost', { content });
 }
 
+// ── Phase 3 API ─────────────────────────────────────────────────────────────
+
+// POST /api/music/upload-cover
+export function uploadAndCover(payload) {
+  return apiPost('/api/music/upload-cover', payload);
+}
+
+// POST /api/music/upload-extend
+export function uploadAndExtend(payload) {
+  return apiPost('/api/music/upload-extend', payload);
+}
+
+// POST /api/music/add-vocals
+export function addVocals(payload) {
+  return apiPost('/api/music/add-vocals', payload);
+}
+
+// POST /api/music/add-instrumental
+export function addInstrumental(payload) {
+  return apiPost('/api/music/add-instrumental', payload);
+}
+
+// POST /api/music/video
+export function generateVideo(payload) {
+  return apiPost('/api/music/video', payload);
+}
+
 // ── 로또 고도화 API ────────────────────────────────────────────────────────────
 
 // GET /api/lotto/stats/performance