node:v8: expose serialize and deserialize round trips

[andrewtdiz]

Summary

v8.serialize(value) and v8.deserialize(buffer) should expose Node's public V8 wire-format round-trip helpers. Perry currently has no public node:v8 namespace implementation, even though the tree contains an internal child-process V8 wire-format serde helper.

Node Behavior

A minimal Node probe shows the public serialization behavior:

const v8 = require("node:v8");
for (const value of [
  { a: 1, b: "x", c: [true, null] },
  new Map([["a", 1]]),
  new Set([1, 2]),
  123n,
  Buffer.from("abc"),
  new Date("2020-01-02T03:04:05Z"),
]) {
  const buf = v8.serialize(value);
  const out = v8.deserialize(buf);
  console.log(Buffer.isBuffer(buf), Object.prototype.toString.call(out));
}

Observed on Node v25.9.0: serialize() returns a Buffer and deserialize() reconstructs objects, maps, sets, BigInts, Buffer/Uint8Array data, dates, and undefined for covered cases. Non-serializable values such as functions, symbols, and WeakMaps throw Error; invalid deserialize inputs such as missing, null, primitives, plain objects, and arrays throw TypeError ERR_INVALID_ARG_TYPE.

Perry Behavior

docs/runtime-parity-gaps.md lists node:v8 as a gap and docs/runtime-parity.md lists v8.serialize(value) / v8.deserialize(buffer) as partial. Source search found no public node:v8 manifest/runtime implementation, while crates/perry-runtime/src/child_process/v8_serde.rs documents an internal wire shape verified against Node's v8.serialize / deserialize for child-process IPC. There is no dedicated test-files/test_parity_v8.ts or test-parity/node-suite/v8 fixture in this checkout.

Suggested PR Cut

Batch this with related issues in:
#2492 - node:v8: diagnostics and serialization parity cut

Good batch candidates:

• node:v8: expose heap statistics shape #3138
• node:v8: expose Serializer and Deserializer class APIs #3294

Do not batch with:

• unrelated modules
• broad subsystem rewrites
• fixes needing different test harnesses
• promise hook APIs
• startup snapshot APIs
• heap snapshot stream/file output
• profiler handle APIs

Acceptance

• A parity/regression test proves v8.serialize() returns a Buffer and v8.deserialize() round-trips representative objects, arrays, maps, sets, BigInts, Buffers/Uint8Arrays, dates, and undefined.
• Non-serializable values and invalid deserialize inputs produce Node-compatible errors for covered cases.
• Public node:v8 dispatch either reuses the internal V8 serde helper where appropriate or documents any intentional wire-format limitation with a focused follow-up.
• Related known-failure/docs/manifest entries are updated if touched.

[andrewtdiz]

I am taking this as part of a node:v8 diagnostics and serialization PR cut with #3138 and #3294.

Intended scope: expose the public node:v8 namespace for serialize / deserialize, diagnostic heap-stat shape helpers, and the Serializer/Deserializer class API using one V8 parity fixture and shared runtime dispatch path.

[andrewtdiz]

Opened PR #3428 to address this in the shared node:v8 diagnostics/serialization surface: #3428