chore(ci): remove codspeed integration

[samzong]

Summary

Remove the CodSpeed workflow so pull requests, pushes to main, and manual dispatches no longer run or upload CodSpeed benchmarks. Remove its badges from both READMEs and its CI claims from the contribution guide and Makefile help.

Keep the benchmark tests and make bench for local use. Deleting the integration is preferable to leaving a disabled workflow because no stable benchmark runner is available and dormant configuration would still require maintenance.

Verification

• make check passed: formatting, vet, lint, and all package tests.
• actionlint passed for the remaining workflows.
• Repository-wide tracked-file search found no remaining CodSpeed references.
• make help displays Run local benchmarks; make -n bench still resolves to go test -bench=. ./....
• go test -run '^$' -bench=. -benchtime=1x ./internal/codegen/backends/openapi3 ./internal/codegen/backends/swagger ./internal/codegen/normalize ./pkg/runtime passed as a benchmark entrypoint smoke test.
• The ordinary CI workflow is unchanged. GitHub main branch rules contain no required CodSpeed check.
• Post-merge GitHub Actions behavior and full benchmark measurements have not been exercised.

Compatibility

No generated command, catalog schema, authentication, request-body, or output behavior changes. Automated CodSpeed performance reporting is removed; local benchmarks remain available.

Checklist

• Tests or focused verification cover the changed surface.
• User-facing behavior changes are documented.
• Generated output under internal/generated/, .cache/, and ad-hoc skills/<cli-name>/ directories is not committed.
• Commits are signed off when this is ready to merge.

[samzong]

@codex review

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-07T09:10:26.774580Z	59a158b	Manual request

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[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Keep them coming!

Reviewed commit: 59a158bd16

ℹ️ About Codex in GitHub

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• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

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