fix: use virsh define for VM creation instead of virt-install

virt-install requires storage pool driver which is not available on this
system. Switched to direct virsh define using XML template which works
without storage pools.

Changes:
- Replaced virt-install with virsh define + start
- Pre-create disk with qemu-img before VM definition
- Copy ISO to /var/lib/libvirt/images with proper ownership
- Use XML template with variable substitution
- VM now appears in virt-manager under QEMU/KVM connection

VM knel-football-test is now running and visible in virt-manager.

💘 Generated with Crush

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

vm/template.xml

@@ -7,7 +7,7 @@
   <os>
     <type arch='x86_64' machine='q35'>hvm</type>
     <loader readonly='yes' secure='@SECURE_BOOT@' type='pflash'>@UEFI_CODE@</loader>
-    <nvram>@UEFI_VARS@</nvram>
+    <nvram template='@UEFI_VARS_TEMPLATE@'/>
     <boot dev='cdrom'/>
     <boot dev='hd'/>
   </os>
@@ -39,7 +39,6 @@
       <readonly/>
     </disk>
     <interface type='user'>
-      <mac address='@MAC_ADDRESS@'/>
       <model type='virtio'/>
     </interface>
     <graphics type='vnc' port='-1' autoport='yes'>