fix: use libvirt session URI consistently, remove QEMU fallback

- All virsh commands now use qemu:///session explicitly
- Removed direct QEMU fallback (libvirt only)
- Added VM XML template in vm/template.xml with variable substitution
- Template generates UUID and MAC address dynamically
- VM is now properly defined AND started in libvirt
- Fixed vm_destroy, vm_console, vm_status, vm_is_running, vm_capture_screen
- Added UUID fallback using /proc/sys/kernel/random/uuid

Fixes issue where VMs were created but not visible/running in virt-manager.

💘 Generated with Crush

Assisted-by: GLM-5 via Crush <crush@charm.land>

vm/template.xml

@@ -0,0 +1,55 @@
+<domain type='kvm'>
+  <name>@VM_NAME@</name>
+  <uuid>@VM_UUID@</uuid>
+  <memory unit='MiB'>@VM_RAM@</memory>
+  <currentMemory unit='MiB'>@VM_RAM@</currentMemory>
+  <vcpu placement='static'>@VM_CPUS@</vcpu>
+  <os>
+    <type arch='x86_64' machine='q35'>hvm</type>
+    <loader readonly='yes' secure='@SECURE_BOOT@' type='pflash'>@UEFI_CODE@</loader>
+    <nvram>@UEFI_VARS@</nvram>
+    <boot dev='cdrom'/>
+    <boot dev='hd'/>
+  </os>
+  <features>
+    <acpi/>
+    <apic/>
+    <smm state='on'/>
+  </features>
+  <cpu mode='host-passthrough' check='none'/>
+  <clock offset='utc'>
+    <timer name='rtc' tickpolicy='catchup'/>
+    <timer name='pit' tickpolicy='delay'/>
+    <timer name='hpet' present='no'/>
+  </clock>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu-system-x86_64</emulator>
+    <disk type='file' device='disk'>
+      <driver name='qemu' type='qcow2'/>
+      <source file='@VM_DISK@'/>
+      <target dev='vda' bus='virtio'/>
+    </disk>
+    <disk type='file' device='cdrom'>
+      <driver name='qemu' type='raw'/>
+      <source file='@ISO_PATH@'/>
+      <target dev='sda' bus='sata'/>
+      <readonly/>
+    </disk>
+    <interface type='user'>
+      <mac address='@MAC_ADDRESS@'/>
+      <model type='virtio'/>
+    </interface>
+    <graphics type='vnc' port='-1' autoport='yes'>
+      <listen type='address' address='127.0.0.1'/>
+    </graphics>
+    <video>
+      <model type='virtio' heads='1' primary='yes'/>
+    </video>
+    <console type='pty'>
+      <target type='serial' port='0'/>
+    </console>
+  </devices>
+</domain>