feat(ts-client): support message-only protos and proto field names

[elzalem]

Summary

This PR extracts the TypeScript-specific work from #126. Closes #133.

Included here:

• add message-only proto support to protoc-gen-ts-client
• add field_names=json|proto support for TS client output
• fix TS client generation for empty request messages
• update TS golden coverage for the new shapes

Why

These changes are self-contained within the TypeScript generator stack and can be reviewed independently from the new cross-language generators.

What Changed

• update cmd/protoc-gen-ts-client
• extend internal/tsclientgen
• adjust shared TS helpers in internal/tscommon
• update the TS server generator integration point as needed

Tests

• env GOTOOLCHAIN=auto go test ./internal/tsclientgen
• env GOTOOLCHAIN=auto go build -o bin/protoc-gen-ts-client ./cmd/protoc-gen-ts-client

[github-actions]

🔍 CI Pipeline Status

❌ Lint: failure
✅ Test: success
✅ Coverage: success
⚠️ Build: skipped
⚠️ Integration: skipped

---

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

[codecov]

Codecov Report

❌ Patch coverage is 71.42857% with 16 lines in your changes missing coverage. Please review.
✅ Project coverage is 5.10%. Comparing base (917521f) to head (ea24e20).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/tscommon/types.go	64.28%	10 Missing ⚠️
internal/tsclientgen/generator.go	73.68%	4 Missing and 1 partial ⚠️
internal/tsservergen/generator.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##            main    #130      +/-   ##
========================================
+ Coverage   3.17%   5.10%   +1.92%     
========================================
  Files         47      47              
  Lines       7485    7732     +247     
========================================
+ Hits         238     395     +157     
- Misses      7243    7305      +62     
- Partials       4      32      +28     

Flag	Coverage Δ
unittests	5.10% <71.42%> (+1.92%)	⬆️

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