feat(service): support native service management on Windows, Linux, and macOS

[Karib0u]

Purpose

Provide the same service-management surface on all supported platforms while keeping platform-specific implementation details isolated.

CLI Surface

rustinel service install
rustinel service uninstall
rustinel service start
rustinel service stop
rustinel service restart
rustinel service status

Scope

• Add a shared internal service backend interface.
• Preserve and improve the Windows Service Control Manager implementation.
• Add Linux systemd support.
• Add macOS launchd system daemon support.
• Add restart and status.
• Use canonical managed binary and configuration paths.
• Validate that required files exist before service installation.
• Make install and uninstall idempotent.
• Keep platform-specific code isolated.

Service Install Requirements

• Register the native service definition.
• Use the managed binary and managed configuration paths.
• Avoid downloading rules.
• Avoid overwriting user configuration.
• Avoid silently copying an executable from a temporary or downloads directory.

Service Uninstall Requirements

• Stop and unregister the service.
• Preserve configuration, rules, logs, and state by default.
• Avoid acting as a full data-purge command.

Normalized Status Values

not-installed
stopped
starting
running
failed
unknown

Acceptance Criteria

• install, uninstall, start, stop, restart, and status work on all supported platforms.
• Service definitions use canonical managed paths.
• install does not download rules or overwrite configuration.
• uninstall preserves user data.
• status reports meaningful normalized states.
• Generated systemd and launchd definitions are covered by tests.
• Windows service behavior is preserved behind the shared interface.
• Mock backend tests cover success, failure, and unknown states.

Dependencies

• feat(config): add portable and managed installation layouts #103

Priority

P0