## Summary

Adds an API-surface polyfill for `v8.startupSnapshot` on `node:v8` so
that
modules destructuring `setDeserializeMainFunction`,
`addSerializeCallback`,
`addDeserializeCallback`, or `isBuildingSnapshot` load without throwing.

Deno does not implement `--build-snapshot` / `--snapshot-blob`, so this
is
not a real snapshot lifecycle:

- `isBuildingSnapshot()` returns `false`.
- `setDeserializeMainFunction(fn, data)` invokes `fn(data)`
synchronously so
  scripts written for snapshot deserialization still execute their entry
  point in plain Deno runs.
- `addSerializeCallback` / `addDeserializeCallback` store the callbacks
but
  never invoke them (there is no serialize/deserialize phase).

The two node_compat tests that exercise the full snapshot lifecycle
(`parallel/test-snapshot-console.js`,
`parallel/test-snapshot-stack-trace-limit.js`)
are marked `ignore: true` with the same reason as the other
`test-snapshot-*`
entries because they need actual `--build-snapshot` / `--snapshot-blob`
support to pass. The minimum required by the issue — exposing
`startupSnapshot` so the destructure no longer throws — is in place.

Closes denoland/orchid#127

## Test plan

- [x] `deno fmt` clean
- [x] `deno lint` clean on changed files
- [x] Manual smoke test: `require('node:v8').startupSnapshot` exposes
the
      4 methods, `isBuildingSnapshot()` returns `false`, and
      `setDeserializeMainFunction(fn)` invokes `fn`
- [x] New unit tests in `tests/unit_node/v8_test.ts` cover the API
surface
- [x] `cargo test --test node_compat -- test-snapshot-console.js` now
reports
      `ignored` instead of failing
- [x] `cargo test --test node_compat -- snapshot-stack-trace-limit.` now
      reports `ignored` instead of failing

Co-authored-by: divybot <[email protected]>
Co-authored-by: Divy Srivastava <[email protected]>