feat(issues): add mostActiveRepo, assigned issues, and caching to Iss…

[vedika76]

Summary

Completes the Issue Metrics widget by adding the missing features from the original issue specification.

Closes #254

Type of Change

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

Changes Made

• Added mostActiveRepo stat to show the repo with the most issues
• Added assigned issues fetching alongside authored issues (deduplicated)
• Added 5-minute caching to reduce GitHub API calls
• Updated GitHubIssueItem and IssuesMetrics interfaces in github.ts
• Updated IssueData interface and UI in IssueMetrics.tsx to show 5 stat cards

How to Test

Steps for the reviewer to verify this works:

1. Sign in to the dashboard
2. Scroll down to the "Issue Analytics" section
3. Verify 5 cards are shown including "Most Active Repo"
4. Verify no errors appear

Screenshots (if UI change)

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

[vercel]

@vedika76 is attempting to deploy a commit to the PRIYANSHU DOSHI's projects Team on Vercel.

A member of the Team first needs to authorize it.