Implement core package manager with component configuration, installer
logic, OS detection, and a command‑line interface for install, remove,
list, and status operations.
- Split package manager into separate modules
- Expose only the installer API
- Simplify BootstrapManager to install components and load config
- Pin ureq to 3.1.2 and add ureq‑proto crate
- Clean up configuration code and remove legacy comments
- Update helper scripts and server start command formatting
Replace `thread_rng` with `rng` and use `random_range` for character
selection. Rename the `component` argument to `_component` in
`PackageManager::download_binary` to suppress an unused‑parameter
warning.
