Closes #

## 🎯 Changes

What changes are made in this PR? Is it a feature or a bug fix?

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## ✅ Checklist

- [ ] I have followed the steps listed in the [Contributing guide](https://github.com/trpc/trpc/blob/main/CONTRIBUTING.md).
- [ ] If necessary, I have added documentation related to the changes made.
- [ ] I have added or updated the tests related to the changes made.


<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit

* **Chores**
  * CI now fails if generated OpenAPI test fixtures are out of date.
  * Test tooling adds per-router on-disk caching to skip unnecessary regeneration and speed workflows.
  * Test watcher now retriggers when package metadata changes.
  * Git ignore updated to exclude cached test artifacts.

* **Documentation**
  * Cleaned and standardized generated doc comments/descriptions in OpenAPI test outputs.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->