workshop-frontend build cannot run its clean task on Windows

## Summary

On Windows, the `workshop-frontend` Vite+ build task cannot get past its `clean:dist` dependency because that task asks Vite+ to execute the POSIX `rm` binary directly.

This also prevents the repository's required `pnpm lint` command from completing on Windows.

## Reproduction

At `3562627` on Windows 11, Node 24.19.0, and pnpm 11.17.0:

```text
> pnpm exec vp run -F @gadgets/workshop-frontend --no-cache build

error: Failed to find executable rm under cwd \packages\workshop-frontend
* cannot find binary path
```

The same failure occurs when the frontend task is reached through `pnpm lint`.

## Cause

#212 added this Vite+ task:

```ts
'clean:dist': { command: 'rm -rf dist', cache: false },
```

Vite+ resolves the task command as an executable, and a normal Windows environment has no `rm` binary. The older `clean` package scripts are different: package-manager scripts go through their platform shell, while this task is launched by Vite+ directly.

## Verified fix

Using Node's built-in filesystem API preserves the recursive, missing-path-tolerant cleanup without requiring a platform-specific executable:

```ts
command: `node -e "require('node:fs').rmSync('dist', { recursive: true, force: true })"`,
```

With that change on the same checkout:

- the targeted frontend build completed, including both TypeScript checks and the production Vite bundle;
- a stale sentinel placed under `dist/` before the run was removed by `clean:dist`;
- the full `pnpm lint` command completed successfully (existing warnings only).

AI tools assisted the investigation and drafting. The failure and verification results above were reproduced locally.

Locate the workshop-frontend Vite+ configuration containing the clean:dist task and reproduce the targeted build on Windows, then run pnpm lint. Done means clean:dist removes a stale dist/ sentinel, the frontend build completes its TypeScript checks and production bundle, and pnpm lint completes with only existing warnings.

Written by the indexing model from the issue text.