fix: enforce validation for grace values within 0-7 range

[VedantMadane]

Summary

fix: reject grace values outside 0-7 with validation error

Changes

• Out-of-range grace was silently clamped to 7.
• Zod now rejects with a validation error.

Fixes #1241

[retenta-bot]

This pull request addresses the issue of handling out-of-range grace values by implementing a validation error instead of silent coercion. This aligns with previous decisions made to ensure consistency and adherence to the API contract. Thank you for your contribution!

[github-actions]

👋 Hey @VedantMadane! Thanks for your interest in contributing to CommitPulse! 🙏

Unfortunately, this PR has been automatically closed because you are not assigned to the linked issue #1241 — [Bug]: grace param accepts values above 7 silently — should return 400.

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