Minor improvements to Terraform & C++ Httplib generators

[wing328]

a follow up pr to #21724, #22949

PR checklist

• Read the contribution guidelines.
• Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
• Run the following to build the project and update samples:

  ./mvnw clean package || exit
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  ./bin/utils/export_docs_generators.sh || exit
  

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  Commit all changed files.
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Summary by cubic

Raises the Go requirement for generated Terraform providers to >= 1.24 and updates all Terraform sample READMEs. Also polishes the C++ Httplib server generator and adds template author credits.

• Refactors

  • C++ Httplib: minor cleanups for naming, enum handling, include selection, and logging; no behavior change expected.
  • Docs: added template creator credits for Terraform and C++ Httplib in the main README.

• Dependencies

  • Terraform provider README template now requires Go >= 1.24; all Terraform sample READMEs updated accordingly.

^{Written for commit 2cd2dc3. Summary will update on new commits.}

[cubic-dev-ai]

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