fix: ensure wasm module matches frontend build

[kxxt]

The frontend is built against the typst_ts_renderer_bg.wasm installed in node_modules. However, the cli ships a prebuilt typst_ts_renderer_bg.wasm from https://github.com/Myriad-Dreamin/typst/tree/assets-book-v0.2.0 . This mismatch can cause wasm load failures(#100).

This PR fixes it by copying the wasm module from node_modules to ensure a single source of truth for typst_ts_renderer_bg.wasm.

Fix #100

[Myriad-Dreamin]

Thank you for contribution. It should help develop with locally built WASM. The weird point is that we want to make cargo install https://github.com/Myriad-Dreamin/shiroa work, so we are shipping the WASM binary with the git submodule. I find it is not satisfied but I have no clue how we should go:

1. continue using git submodule
2. bundle the assets in some crate and upload them to crates.io
3. don't allow cargo install https://github.com/Myriad-Dreamin/shiroa anymore.

[kxxt]

The weird point is that we want to make cargo install https://github.com/Myriad-Dreamin/shiroa work, so we are shipping the WASM binary with the git submodule. I find it is not satisfied but I have no clue how we should go:

1. continue using git submodule

2. bundle the assets in some crate and upload them to crates.io

3. don't allow `cargo install https://github.com/Myriad-Dreamin/shiroa` anymore.

I think there is another way to go but it would require users to have yarn installed on their machine.

We can remove the independent build script and build the frontend in build.rs. POC: cargo install --git https://github.com/kxxt/shiroa --branch build-frontend-in-build.rs

kxxt@1453507

[Myriad-Dreamin]

Sorry I don't know the reason but I thought you requested to merge kxxt@1453507. I think it is okay to copy the wasm module in build-from-source.