* fix(scripts): enable shell mode on Windows for .cmd shim resolution

On Windows, tools like `bun`, `npm`, `turbo`, and `bunx` are installed
as `.cmd` shims. Node's `child_process.spawn` cannot resolve these
without `shell: true`, causing `PlatformError: NotFound` on fresh
builds where there is no Turbo cache.

Add `shell: process.platform === "win32"` to all ChildProcess.make
calls in cli.ts, dev-runner.ts, and build-desktop-artifact.ts.

Closes #474

* docs: add comments explaining Windows shell spawn requirement

* docs: add shell spawn comments to remaining call sites