Add audio format selection for audio-only downloads

Introduces settings and UI for forcing audio format conversion on audio-only downloads, including support for selecting preferred audio formats. Updates language files for all supported languages, adds config options, and passes new settings through the downloader and main app logic.

src/gui/ytsage_gui_main.py

@@ -125,6 +125,8 @@ class YTSageApp(QMainWindow, FormatTableMixin, VideoInfoMixin):  # Inherit from
         # Initialize output format settings
         self.force_output_format = ConfigManager.get("force_output_format") or False
         self.preferred_output_format = ConfigManager.get("preferred_output_format") or "mp4"
+        self.force_audio_format = ConfigManager.get("force_audio_format") or False
+        self.preferred_audio_format = ConfigManager.get("preferred_audio_format") or "best"
         # Track if video analysis is completed
         self.analysis_completed = False
 
@@ -898,6 +900,8 @@ class YTSageApp(QMainWindow, FormatTableMixin, VideoInfoMixin):  # Inherit from
             geo_proxy_url=self.geo_proxy_url,  # Pass the geo-verification proxy URL
             force_output_format=self.force_output_format,  # Pass force output format setting
             preferred_output_format=self.preferred_output_format,  # Pass preferred format
+            force_audio_format=self.force_audio_format,  # Pass force audio format setting
+            preferred_audio_format=self.preferred_audio_format,  # Pass preferred audio format
         )
 
         # Connect signals