fix(recall): scope text fallback to individual requests

[kuitos]

A single StructuredOutputError currently switches a V1 host permanently to text output, affecting later recall requests in the same session and in other sessions served by that host. Retry only the failing request once as text, so later requests can use structured output again after a transient failure. Models that consistently fail structured output will now require two attempts per recall request; no model-capability cache is inferred from an individual failure.

Clarify the readOnly guarantee in the README and AGENTS.md: it prevents writes by this plugin, including persistent state updates. The host's shell/file-editing tools and other plugins require separate host permissions or filesystem access controls for enforced read-only access.

Follow-up to #56.

Validation:

• bun test: 348 passed, 2 skipped.
• bun run lint, bun run typecheck, and bun run build: passed.
• bun run evals: 7/7 passed.
• Regression coverage for repeated structured-output failures, recovery in the same and another session, and a failed text retry stopping after one retry. The three request-scope regression cases fail against the previous implementation and pass with this change.
• Built JavaScript contains no runtime imports of either host SDK; no module-level Map/Set instances were added.

No live-model validation was performed.

[github-actions]

🎉 This PR is included in version 2.2.1 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀