docs: update README with ISO testing commands

Add ISO testing section with libvirt/virsh commands (create, console, status, stop, destroy, list). Update project files table to include test-iso.sh script.

💘 Generated with Crush

Assisted-by: GLM-4.7 via Crush <crush@charm.land>

README.md

@@ -19,6 +19,7 @@
 | File | Purpose |
 |------|---------|
 | `run.sh` | Main entry point (build/test/lint/clean/iso) |
+| `test-iso.sh` | ISO testing with libvirt/virsh VMs |
 | `Dockerfile` | Build environment |
 | `config/` | Live-build configuration |
 | `tests/` | BATS test suite |
@@ -76,6 +77,16 @@ tail -50 /tmp/knel-iso-build.log | grep "P:"
 ls -lh output/
 ```
 
+### ISO Testing (libvirt/virsh)
+```bash
+./test-iso.sh create              # Create and boot test VM
+./test-iso.sh console             # Connect to VM console
+./test-iso.sh status              # Show VM status
+./test-iso.sh stop                # Stop VM
+./test-iso.sh destroy             # Remove VM
+./test-iso.sh list                # List all test VMs
+```
+
 ---
 
 ## Project Overview