Add output format selection to settings

Introduces new settings for forcing output format when merging videos, allowing users to select a preferred format (mp4, webm, mkv). Updates all language files with relevant translations, adds UI controls in the settings dialog, persists settings via ConfigManager, and passes options through the download workflow to yt-dlp.

languages/id.json

@@ -277,7 +277,14 @@
     "update_frequency_group": "Frekuensi pembaruan",
     "save_settings": "Simpan pengaturan",
     "settings_saved_successfully": "✅ Pengaturan berhasil disimpan!",
-    "error_saving": "❌ Kesalahan menyimpan pengaturan: {error}"
+    "error_saving": "❌ Kesalahan menyimpan pengaturan: {error}",
+    "output_format_settings": "Pengaturan Format Output",
+    "force_output_format": "Paksa format output saat menggabungkan",
+    "preferred_format": "Format yang disukai:",
+    "force_format_help": "Jika diaktifkan, video yang digabungkan akan dikonversi ke format pilihan Anda. Nonaktifkan untuk membiarkan yt-dlp memutuskan secara otomatis.",
+    "format_mp4": "MP4 (Paling kompatibel)",
+    "format_webm": "WebM (Modern, terbuka)",
+    "format_mkv": "MKV (Kaya fitur)"
   },
   "main_ui": {
     "url_placeholder": "Masukkan URL video atau playlist YouTube",