docs: add setup troubleshooting checklist

[dashitongzhi]

Summary

• add a setup troubleshooting section to the README
• document ffmpeg/ffprobe checks, uv/pip fallback, Python version, .env/API key setup, skill symlink checks, and smoke checks

Testing

• ran a small Python assertion to confirm the new README section and key troubleshooting entries are present

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Summary by cubic

Added a setup troubleshooting checklist to the README to help unblock common install issues. Covers ffmpeg/ffprobe checks, Python 3.10+, uv/pip fallback, .env and ELEVENLABS_API_KEY setup, skill symlink verification, and quick smoke tests.

^{Written for commit 428dca3. Summary will update on new commits.}

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[cubic-dev-ai]

No issues found across 1 file

_{Re-trigger cubic}