fix(openapiv3): tag YAML example scalars

[SebastienMelki]

Summary

• Tag OpenAPI YAML example scalar nodes according to schema type
• Preserve string examples that look like numbers or timestamps as YAML strings
• Apply the helper to scalar field examples, wrapper field examples, and header examples
• Add regression coverage/goldens for direct scalar and wrapper string examples
• Include minimal lint-only cleanups needed for make lint to pass

Fixes #244

Verification

• make lint
• go test -count=1 ./internal/openapiv3 ./internal/tsservergen ./internal/tsclientgen
• go test -count=1 ./internal/openapiv3

[github-actions]

🔍 CI Pipeline Status

✅ Lint: success
✅ Test: success
✅ Coverage: success
✅ Build: success
✅ Integration: success

---

📊 Coverage Report: Available in checks above
🔗 Artifacts: Test results and coverage reports uploaded

[codecov]

Codecov Report

❌ Patch coverage is 70.58824% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 28.88%. Comparing base (fa45cf4) to head (bfa4e2a).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/openapiv3/types.go	69.23%	7 Missing and 1 partial ⚠️
internal/tsservergen/generator.go	75.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #245      +/-   ##
==========================================
+ Coverage   28.76%   28.88%   +0.12%     
==========================================
  Files          75       75              
  Lines       13146    13157      +11     
==========================================
+ Hits         3781     3800      +19     
+ Misses       9166     9160       -6     
+ Partials      199      197       -2     

Flag	Coverage Δ
unittests	28.88% <70.58%> (+0.12%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[SebastienMelki]

APPROVED