* move `oxide/crates` to `crates`
* ignore `target/` folder
* ensure pnpm points to `crates` instead of `oxide/crates`
* ensure all paths point to `crates` instead of `oxide/crates`
* update `oxide/crates` -> `crates` path in workflows
* use correct path in .prettierignore
* rename `crates/core` to `crates/oxide`
* remove oxide folder
* fix test script to run `cargo test` directly
