Integrations: Paginate GitHub branches API

[nisshchayarathi]

Summary
Avoid missing branches on large repos.

Context

Area: GitHub integration
Related: lib/services/githubService.ts

Acceptance criteria

• Implement pagination
• Stop when fewer than per_page returned
• Add basic error handling

[tmdeveloper007]

This issue has been fixed in PR #2593: #2593

The fix includes:

• Targeted code changes addressing the root cause
• TypeScript compilation passes
• All CI checks passing

Please review and merge.