fix: OS template type matching for LXC/KVM nodes

- Add is_lxc column to ext_proxmox_oses for tracking template type
- OS model now has vmType() helper returning 'lxc' or 'qemu'
- Install uses OS template's type for clone API path (not node type)
- createServer validates OS type matches node type before provisioning
- calculateNode filters nodes by LXC/KVM type based on selected OS
- Reinstall OS list filtered to only show matching template types
- Admin location OS repeater now has LXC Template checkbox

extensions/Servers/Proxmox/Models/OS.php

@@ -13,5 +13,18 @@ class OS extends Model
         'name',
         'vm_id',
         'location_id',
+        'is_lxc',
     ];
+
+    protected $casts = [
+        'is_lxc' => 'boolean',
+    ];
+
+    /**
+     * Get the VM type string for Proxmox API paths.
+     */
+    public function vmType(): string
+    {
+        return $this->is_lxc ? 'lxc' : 'qemu';
+    }
 }