feat(admin): music library admin + fix CRM analytics UTC

- /admin/music: list / upload / delete studio audio tracks (content-svc
  GET/POST/DELETE /v1/music) — fills the legacy music-library gap
- fix: CRM analytics coerced query-bound dates to UTC (Npgsql timestamptz
  rejects Kind=Unspecified) — endpoint was returning 400

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

messages/en.json

@@ -328,7 +328,8 @@
       "marketing": "Marketing",
       "crm": "CRM",
       "ranking": "Ranking",
-      "stats": "Dashboard"
+      "stats": "Dashboard",
+      "music": "Music"
     },
     "appAdminNodesPage": {
       "title": "Render Nodes",

messages/fa.json

@@ -328,7 +328,8 @@
       "marketing": "بازاریابی",
       "crm": "مدیریت مشتریان",
       "ranking": "رتبه‌بندی",
-      "stats": "داشبورد"
+      "stats": "داشبورد",
+      "music": "موسیقی"
     },
     "appAdminNodesPage": {
       "title": "نودهای رندر",