Node.js v25 provides a built-in localStorage on globalThis, but without
`--localstorage-file` it is an empty object lacking getItem/setItem.
The existing check `!("localStorage" in globalThis)` passes, so the
polyfill is skipped and the CLI crashes with:
TypeError: localStorage.getItem is not a function
Check for getItem as well so the polyfill is applied when the native
implementation is incomplete.
- Fixed flaky timing issues in P2P synchronisation.
- Fixed more binary file handling issues in CLI.
### Tests
- Rewrite P2P end-to-end tests to use the CLI as host.
