fix(ext/crypto): support structuredClone for CryptoKey (#32674)
## Summary
- Enables `structuredClone()` and `postMessage()` for `CryptoKey`
objects using the cloneable resource registry from #32672
- Works for all key types (AES, RSA, HMAC, EC, Ed25519, X25519, X448)
including **non-extractable** keys
- Clones internal key data directly, bypassing the public `exportKey`
API
Closes #12734
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Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
