Chore: Update references from master/0.34.x to main

[loks0n]

Summary

Follow-up to #241 now that main is the default branch.

• ci.yml push trigger: [master, "*.x"] → [main].
• CONTRIBUTING.md: two references to master updated to main.
• README.md: replace dead Travis CI badge with a GitHub Actions badge pointing at the ci.yml workflow on main, and fix the CONTRIBUTING.md link.

Test plan

• CI runs green on this PR
• After merge, the new Actions badge resolves to the real workflow status

🤖 Generated with Claude Code

[greptile-apps]

Greptile Summary

This PR updates stale master references to main across the CI workflow trigger, CONTRIBUTING.md, and README.md, and replaces the dead Travis CI badge with a live GitHub Actions badge. The removal of the "*.x" push trigger pattern is safe — no remote maintenance branches matching that pattern currently exist in the repository.

Confidence Score: 5/5

Safe to merge — all changes are housekeeping with no functional risk.

All three files contain straightforward reference updates; no *.x branches exist so dropping that trigger pattern has no impact; README badge replacement is correct.

No files require special attention.

Important Files Changed

Filename	Overview
.github/workflows/ci.yml	Push trigger updated from [master, "*.x"] to [main], dropping CI coverage for versioned maintenance branches (e.g., 0.34.x)
CONTRIBUTING.md	Two references to master branch updated to main — clean, no issues
README.md	Travis CI badge replaced with GitHub Actions badge; Contributing guide link updated from master to main — clean, no issues

_{Reviews (1): Last reviewed commit: "Chore: Update references from master/0.3..." | Re-trigger Greptile}

[github-actions]

k6 benchmark

Throughput	Requests	Fail rate	p50	p95
8838 req/s	618685	0%	4.18 ms	11.31 ms