fix(api): clamp days query param in hourly contributions route

[Honey-pg]

Summary

Parse days as an integer and clamp to 1..365 in GET /api/metrics/contributions/hourly, matching other metrics routes and preventing malformed input (negatives, fractions, Infinity, huge values) from producing invalid date windows or 502 errors.

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#Closed #2193

Type of Change

• Bug fix
• New feature
• Documentation update
• Refactor / code cleanup

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Changes Made

• Replaced Number() parsing with parseInt + default/clamp logic in src/app/api/metrics/contributions/hourly/route.ts
• Added test/contributions-hourly.test.ts covering negative, fractional, zero, unbounded, and missing days inputs

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How to Test

1. Run npm run type-check
2. Run npx vitest run test/contributions-hourly.test.ts
3. Optionally hit the route with malformed query params and confirm 200 responses with clamped days:
   • ?days=-30 → days: 1
   • ?days=Infinity → days: 30
   • ?days=999999 → days: 365
   • no param → days: 30

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Checklist

• Linked issue in summary
• npm run lint passes locally
• No TypeScript errors (npm run type-check)
• Self-reviewed the diff
• Added/updated tests if applicable

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Additional Notes

Aligns with the existing validation pattern in contributions/route.ts, repos/route.ts, and productive-hours/route.ts. Hourly contributions keeps its default of 30 days when the param is missing or invalid.

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