ssh keys, edit command, python SDK

[iicky]

• authorize recipients from SSH key files (ssh:path)
• murk edit command for editing secrets in $EDITOR
• Python SDK via PyO3 (pip install murk-secrets)
• Python CI workflow with PyPI trusted publishing
• workflow files renamed from .yml to .yaml
• VHS demo tape and Makefile test for SSH flow
• README updates

[codecov]

Codecov Report

❌ Patch coverage is 0% with 165 lines in your changes missing coverage. Please review.
✅ Project coverage is 52.57%. Comparing base (78fe2c1) to head (dcc6c2b).
⚠️ Report is 16 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/main.rs	0.00%	165 Missing ⚠️

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