Constrain TResponse.json to JSON values

[ghost]

Summary

• constrain TResponse.json to recursively JSON-compatible values
• add compile-time coverage for accepted and rejected response values
• update form-data mocks to avoid returning potentially non-JSON File values
• add a changeset for the affected packages

Verification

• git diff --check passes
• Local TypeScript/Vitest binaries were unavailable in the sandbox; CI should run the package checks

---

Resolves #426

🤖 Open this thread in ColorCode

[changeset-bot]

🦋 Changeset detected

Latest commit: ea94c64

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 5 packages

Name	Type
@toapi/common	Patch
@toapi/server	Patch
@toapi/client	Patch
@toapi/worker	Patch
@toapi/react	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[ghost]

✅ Review passed

Every acceptance criterion is met and every review comment is resolved.
ColorCode has nothing outstanding on this pull request.

[ghost]

✅ Review passed

Every acceptance criterion is met and every review comment is resolved.
ColorCode has nothing outstanding on this pull request.