fix(standard-schema): preserve validator bindings across helpers (#2483)

## Summary

- Bind all four Standard Schema helpers to the same validator metadata
used for strict schema generation.
- Preserve explicit-schema laziness, original method receivers, and
existing tool-option getter ordering.
- Add focused integrated regressions for fresh metadata, converter
mutation, validator swapping, and malformed JSON.

## Validation

- Node 22.23 and Node 26.7: 6,541 handwritten and 556 generated tests on
each runtime.
- Canonical lint, strict TypeScript 6, published TypeScript 4.9/6
declarations, and package builds on both runtimes.
- publint and installed packed-package CJS/ESM adversarial helper checks
on both runtimes.