feat: support network boot (PXE) for VM interfaces (#1176)

Add an "Enable network boot (PXE)" option to bridge network interfaces and
a VM-level choice to place network boot devices before or after volumes.
The form now owns interface boot order: enabled NICs get sequential boot
orders ahead of or behind the volumes, and a stale bootOrder is no longer
inherited from the old spec.

This also fixes editing a VM whose interface bootOrder was set in YAML
(the documented workaround): the form used to renumber disks from 1 while
keeping the NIC's bootOrder, producing a duplicate that KubeVirt rejects.

The boot order shown on the VM, snapshot and backup detail pages now
includes network interfaces.

Related: harvester/harvester#3325

Signed-off-by: Alejandro Bonilla <abonilla@suse.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

pkg/harvester/edit/kubevirt.io.virtualmachine/VirtualMachineNetwork/base.vue

@@ -2,6 +2,7 @@
 import InputOrDisplay from '@shell/components/InputOrDisplay';
 import { LabeledInput } from '@components/Form/LabeledInput';
 import LabeledSelect from '@shell/components/form/LabeledSelect';
+import { Checkbox } from '@components/Form/Checkbox';
 
 import { clone } from '@shell/utils/object';
 import { _CREATE, _VIEW } from '@shell/config/query-params';
@@ -33,7 +34,7 @@ export default {
   emits: ['update'],
 
   components: {
-    LabeledInput, LabeledSelect, InputOrDisplay
+    LabeledInput, LabeledSelect, InputOrDisplay, Checkbox
   },
 
   props: {
@@ -169,6 +170,7 @@ export default {
         this.value.isPod = true;
         this.value.macAddress = '';
         this.value.staticIp = '';
+        this.value.networkBoot = false;
       } else {
         this.value.isPod = false;
       }
@@ -285,6 +287,22 @@ export default {
       </div>
     </div>
 
+    <div
+      v-if="!isMasquerade"
+      data-testid="input-hen-networkBoot"
+      class="row mb-20"
+    >
+      <div class="col span-12">
+        <Checkbox
+          v-model:value="value.networkBoot"
+          :label="t('harvester.virtualMachine.network.networkBoot.label')"
+          :tooltip="t('harvester.virtualMachine.network.networkBoot.tip')"
+          :mode="mode"
+          @update:value="update"
+        />
+      </div>
+    </div>
+
     <div v-if="!isMasquerade && isSingle">
       <div class="row mb-20">
         <a