feat(ext/node): implement node:repl module (#32799)
## Summary
- Replaces the stub `node:repl` implementation with a working
`REPLServer` that extends readline's `Interface`
- Supports TTY-based REPL usage with eval via
`vm.Script`/`vm.createContext`, built-in commands (`.break`, `.clear`,
`.exit`, `.help`, `.save`, `.load`, `.editor`), context management with
`_` and `_error` tracking, editor mode, error handling, and multiline
input
- `.editor` command now registered unconditionally (no-op in
non-terminal mode), matching Node.js behavior
- 39 node compat tests now pass out of 104 total REPL tests (up from 1)
---------
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
