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();
+}

tests/gpu.rs

@@ -0,0 +1,29 @@
+use lapctl::commands::gpu::{generate_xrandr_script, xorg_amd, xorg_intel};
+
+#[test]
+fn test_xorg_intel_generation() {
+    let output = xorg_intel("01:00.0");
+    assert!(output.contains(r#"Identifier "intel""#));
+    assert!(output.contains(r#"BusID "01:00.0""#));
+}
+
+#[test]
+fn test_xorg_amd_generation() {
+    let output = xorg_amd("02:00.0");
+    assert!(output.contains(r#"Identifier "amdgpu""#));
+    assert!(output.contains(r#"BusID "02:00.0""#));
+}
+
+#[test]
+fn test_xrandr_script() {
+    let intel_str = "intel".to_string();
+    let script_with_intel = generate_xrandr_script(Some(&intel_str));
+    assert!(
+        script_with_intel.contains(r#"xrandr --setprovideroutputsource "modesetting" NVIDIA-0"#)
+    );
+
+    let script_without_igpu = generate_xrandr_script(None);
+    assert!(
+        script_without_igpu.contains(r#"xrandr --setprovideroutputsource "modesetting" NVIDIA-0"#)
+    );
+}