feat(tests): add CLI and GPU command tests

Add tests for CLI argument parsing and GPU command generation to increase coverage and ensure future changes don't break functionality.

New Features
- Add unit test `verify_cli` to ensure Clap command is built correctly.
- Add unit tests for `xorg_intel`, `xorg_amd`, and `generate_xrandr_script` functions.
- Validate that generated Xrandr scripts contain expected provider settings.

Enhancements
- none

Bug Fixes
- none

tests/cli.rs

@@ -0,0 +1,7 @@
+use clap::CommandFactory;
+use lapctl::cli::Cli;
+
+#[test]
+fn verify_cli() {
+    Cli::command().debug_assert();
+}