feat: add audio conversion script and enhance audio token handling for .opus files

package.json

@@ -8,6 +8,8 @@
   "scripts": {
     "start": "node src/server/index.js",
     "dev": "nodemon src/server/index.js",
+  "audio:convert": "node scripts/convert-to-opus.js",
+  "audio:convert:dry": "node scripts/convert-to-opus.js --dry-run",
     "years:resolve": "node scripts/resolve-years.js",
     "years:resolve:10": "node scripts/resolve-years.js --max 10",
     "years:force": "node scripts/resolve-years.js --force",
@@ -27,6 +29,7 @@
   },
   "devDependencies": {
     "@eslint/js": "^9.11.1",
+  "ffmpeg-static": "^5.2.0",
     "eslint": "^9.11.1",
     "eslint-config-prettier": "^9.1.0",
     "eslint-plugin-import": "^2.29.1",