Fixes#10197
# Important Notes
From now on, package installation will be using `pnpm install`. Installing it globally is fine for convenience, but it can also be used as `corepack pnpm install` without having to install anything other than node. For now, all other scripts are still invoked using `npm`, so we can still invoke them with usual `--workspace` setting. As far as I can tell that doesn't really have any other side effects and is identical as running the script through `pnpm run` in respective workspace project subdirectory.
- Significantly flattens directory structure of `lib/dashboard/`
# Important Notes
- Basic testing done on:
- dashboard's `npm run dev` which (since quite recently) uses Vite.
- specifically: `npm run dev` in `app/ide-desktop/lib/dashboard`, OR `npm run dashboard:dev` in `app/ide-desktop`
- dashboard's bundle script (`npm run build`) which uses ESBuild.
- GUI2's own entry point (GUI2's `npm run dev`).
- `./run ide build`
- `./run ide watch`
- `./run ide2 build`
- `./run gui watch`
