Separate wasm-only repository named 't-ruby-wasm'

[yhk1038]

Background

1. An outdated wasm prototype codebase currently exists in this repository.
2. It is used in the playground on the website (https://type-ruby.github.io), but has been broken for a long time.
3. Meanwhile, t-ruby's syntax and implementation have evolved significantly.
4. The wasm implementation will inevitably need to be separated at some point.
5. We've decided to separate the wasm implementation now before it's too late.

Goals

6. The primary goal of the wasm implementation is to maintain stable performance for previewing the latest version of t-ruby syntax.
7. However, we need to carefully consider how the wasm implementation can closely track and respond to frequent spec changes and version releases of t-ruby.

[yhk1038]

7. as solution, it might be workflow started by t-ruby repo woks for wasm build process. (just idea, not proved)