Add systemd user service and CLI wrapper for remote-touchpad

This commit introduces a complete systemd user service setup for
remote-touchpad, eliminating the need for users to manually manage
the binary process. Key additions:

- New rts CLI wrapper script providing a user-friendly interface
  for service management without requiring root access
- Systemd service file for proper background operation with
  restart policies and dependency management
- Service management commands: install, start, stop, status,
  restart, and uninstall
- URL extraction and QR code generation via the url command
- Service log viewing via the log command

The installation process now:
1. Verifies Go is installed
2. Builds the remote-touchpad binary with appropriate tags
3. Installs service files to ~/.config/systemd/user/
4. Installs the binary to ~/.local/bin/
5. Enables and starts the service automatically

The README has been updated with comprehensive installation
instructions for the new user service approach.

README.md

@@ -23,6 +23,35 @@ Supports Flatpak's RemoteDesktop portal (for Wayland), Windows and X11.
     go install github.com/unrud/remote-touchpad@latest
     ```
 
+## Linux User Service Installation
+
+To install remote-touchpad as a user-specific systemd service (no root access required):
+
+1. Clone the repository and navigate to the project directory:
+
+   ```sh
+   git clone https://github.com/Unrud/remote-touchpad.git
+   cd remote-touchpad
+   ```
+
+2. Install the service using the provided wrapper script (no sudo required):
+
+   ```sh
+   ./rts install
+   ```
+
+3. Access the service:
+
+   * View service status: `./rts status`
+   * Get URL: `./rts url`
+   * View logs: `./rts log`
+   * Stop service: `./rts stop`
+   * Start service: `./rts start`
+   * Restart service: `./rts restart`
+   * Uninstall: `./rts uninstall`
+
+The service will run in the background and maintain a persistent connection with URL and QR code accessible via the `url` command.
+
 ## Screenshots
 
 ![screenshot 1](https://raw.githubusercontent.com/Unrud/remote-touchpad/master/screenshots/1.png)