[atomiechen]

Summary

• Add @pydantic-socketio/codegen to turn the existing AsyncAPI contract into native Socket.IO TypeScript event types for both TypeScript clients and servers.
• Preserve Pydantic model names and Python handler argument names in generated types. Deduplicate repeated schemas, distinguish different models with the same title, and accept earlier formatVersion 1 contracts without argument names.
• Support Node 18, 20, 22, 24, and 26; verify both Python server → TypeScript client and Python client → TypeScript server against real Socket.IO peers and ACKs.
• Keep Python and codegen release workflows separate. The npm package remains private and unreleased.

Verification

• uv run --locked --no-sync pytest -q: 63 passed.
• Ruff and Pyright: passed.
• npm test --prefix packages/codegen: generated types compile, 12 incorrect uses fail type-checking, and both live exchange directions pass.
• Local Node 18/20/22/24/26 runs and clean npm tarball installations: passed.
• Fresh Python wheel and npm tarball also passed the independent local review exercise.

Release boundary

This PR does not publish the npm package. Its package.json remains private: true; 0.1.0 is the planned first public version. A separate release change can set public metadata, version, and a codegen-vX.Y.Z tag after review. The manual release workflow depends on atomiechen/reusable-workflows#1 being merged first. No release workflow has been dispatched.