feat: add PATH fix for macOS, multi-language detection, and clip open/reveal actions

[latif5]

Summary of Changes

1. macOS PATH & Binary Discovery:

   • Fixed an issue where packaged .app bundles on macOS failed to find ffmpeg, ffprobe, yt-dlp, and whisper due to the restricted environment PATH assigned by macOS launch services.
   • Added startup PATH extension and resolve_binary() fallback across standard Homebrew (/opt/homebrew/bin, /usr/local/bin) and user bin paths.

2. Multi-Language Transcription Auto-Detection:

   • Added detect_language=true to the Deepgram Nova-2 listening endpoint so non-English audio (such as Indonesian, Spanish, French, Japanese, etc.) is transcribed accurately instead of forcing English.

3. Clip Open & Reveal Actions:

   • Added Open Clip button and interactive thumbnail play action to open rendered short video clips directly in the OS default media player.
   • Added Finder / Reveal in Finder button to reveal cut video files in macOS Finder / file manager.
   • Implemented native cross-platform open_file and show_in_folder Tauri backend commands.