- Added flutter/macos/Runner/custom.txt with default-settings.enable-audio=N
- Added custom.txt to Xcode Copy Bundle Resources (PBXResourcesBuildPhase)
- RustDesk's load_custom_client() reads this file and injects into DEFAULT_SETTINGS
- Users can still toggle 'Enable audio' in Settings; this just flips the default
This addresses the user's request to disable all 4 audio behaviors by default
(play remote sound, hear remote mic, voice call, capture host audio), all of
which share the single 'enable-audio' option.
xuwenwei