Update Automated Fidelity Verification constraints

[beginwebdev2002]

Updates vibe-check-runner.js to conform to new requirements for the daily fidelity verification task:

1. Discover modified or new .md files using git log and git ls-files
2. Generate unique filenames to avoid state collisions in AST validation.
3. Commit with strictly [chore: fidelity-pass] upon successful (>=95%) verification.

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PR created automatically by Jules for task 18257993350744155641 started by @beginwebdev2002

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