Bun parity: finish core Web Crypto lifecycle and validation

Tracks the copied Bun corpus gap at position 4096: js/web/crypto/web-crypto.test.ts.

Scope:

• preserve crypto.subtle under assignment while accepting the setter
• expose native SHA-1/SHA-2 digest behavior to the corpus adapter and model the child digest/event-loop fixture
• align CryptoKey / SubtleCrypto constructor metadata and branding
• settle JWK unwrap parse failures with structured DataError / TypeError rejections and causal stacks
• preserve AES/HMAC behavior and oversized BufferSource rejection
• add Ed25519 key metadata without a namedCurve field

Focused verification is currently 10 passed, 0 failed, 0 unsupported. The issue will close after permanent queue/build validation and push.

Implemented and pushed in 7295618c3 (fix(crypto): complete Web Crypto lifecycle parity).

Delivered:

• no-op crypto.subtle setter that preserves the original object
• native one-shot SHA bridge for arbitrary corpus digest inputs
• validated Web Crypto child digest adapter with structured WebCryptoChildError metadata and causal stacks
• CryptoKey / SubtleCrypto naming and prototype branding
• settled JWK unwrap failures (DataError for malformed JSON, TypeError for missing kty) with operation metadata and causes
• Ed25519 key-pair/import metadata without namedCurve

Verification:

• js/web/crypto/web-crypto.test.ts: 10 passed, 0 failed, 0 unsupported
• permanent HTTP/web tail queue: passed
• clean zig build --cache-dir /private/tmp/home-zig-abi-cache: passed

Only the intended adapter registration hunk was committed; pre-existing local adapter edits were left unstaged.