Stop treating quoted eval in commit messages as shell eval

[TheGreatAxios]

Summary

• Quoted eval inside git commit -m is no longer hard-denied as a shell eval.
• Double-quoted command substitution eval still denies. Nested leftover is CL-6571.

Verification

• bun test src/shell/run-shell-authz.test.ts passes (65 tests)

Fixes CL-6551

[linear-code]

CL-6551