Windows: FFmpeg detection fails in doctor/render while ffmpeg is on PATH #333

Describe the bug

On Windows, HyperFrames fails to detect FFmpeg even when ffmpeg is available in PATH and executable from both PowerShell and Node.js.

npx hyperframes doctor shows FFmpeg Not found, while FFprobe is detected correctly from the same bin directory. npx hyperframes render then fails with FFmpeg not found.

Link to reproduction

N/A (minimal reproducible steps included below; can provide a public repro repo if required)

Steps to reproduce

1. Install FFmpeg on Windows and add the FFmpeg bin directory to PATH.
2. Verify ffmpeg is available:
   • where ffmpeg
   • ffmpeg -version
3. Run npx hyperframes doctor.
4. Run npx hyperframes render --quality high --output renders/test.mp4.

Expected behavior

• npx hyperframes doctor should detect FFmpeg.
• npx hyperframes render should proceed with encoding.

Actual behavior

• doctor reports:
  • ? FFmpeg Not found
  • ? FFprobe ... (detected)
• render fails with:
  • FFmpeg not found

Environment

hyperframes doctor

  ? Version          0.4.6 (latest)
  ? Node.js          v24.14.1 (win32 x64)
  ? CPU              24 cores ? AMD Ryzen 9 9900X 12-Core Processor @ 4400MHz
  ? Memory           31.1 GB total ? 14.6 GB free
  ? Disk             437.3 GB free
  ? Environment      non-TTY
  ? FFmpeg           Not found
  ? FFprobe          ffprobe version 2026-01-26-git-fe0813d6e2-full_build-www.gyan.dev
  ? Chrome           bundled headless shell detected

Additional checks from the same shell session (paths redacted):

where ffmpeg
C:\<machine-path>\ffmpeg\bin\ffmpeg.exe
C:\Users\<user>\...\ffmpeg\bin\ffmpeg.exe

ffmpeg -version
ffmpeg version 2026-01-26-git-fe0813d6e2-full_build-www.gyan.dev

node -e "const {spawnSync}=require('child_process'); const r=spawnSync('ffmpeg',['-version'],{encoding:'utf8'}); console.log(r.status)"
0

Additional context

• This appears to be a Windows-specific FFmpeg detection inconsistency in HyperFrames 0.4.6.
• Detection works for ffprobe but not for ffmpeg under the same PATH conditions.
• Happy to test a patch or run additional diagnostics.