Port Bun advanced structured clone class modes

Tracks Bun corpus position 4230 (js/web/workers/structuredClone-classes.test.ts).

Completed in 78529f5:

• Export structuredCloneAdvanced from bun:internal-for-testing.
• Implement default/worker/window realm behavior across transfer and storage modes.
• Detach listed ArrayBuffers while preserving clone bytes.
• Preserve ordinary BunFile metadata and BlockList shared state, while storage/transfer preparation produces empty host-object records.
• Reject non-transferable listed host objects with structured DataCloneError context (runtimeCode, operation, phase, context, valueType, cause, source stack).
• Preserve BunFile metadata through non-enumerable implementation slots.
• Extend permanent structured clone regression coverage.

Verification: position 4230 passes 57/57 with 0 failed, 0 todo, and 0 unsupported; the permanent filtered Zig regression also passes.

Completed and pushed in 78529f5. The upstream class/context matrix passes 57/57 and the permanent regression is green.