refactor: Clean checkin override parsing and require node type in frontend configuration modal

drb-frontend/components/NodeConfigModal.tsx

@@ -20,7 +20,7 @@ export function NodeConfigModal({ node, systems, onClose }: Props) {
   const [systemId, setSystemId] = useState(node.assigned_system_id ?? "");
   const [preset, setPreset] = useState(node.hardware_preset ?? "rtl-sdr-v3");
   const [ppm, setPpm] = useState(node.ppm_override ? String(node.ppm_override) : "0");
-  const [nodeType, setNodeType] = useState(node.node_type ?? "fixed");
+  const [nodeType, setNodeType] = useState(node.node_type ?? "");
   const [enforceTimeout, setEnforceTimeout] = useState(node.enforce_override_timeout ?? true);
   const [saving, setSaving] = useState(false);
   const [error, setError] = useState<string | null>(null);
@@ -107,12 +107,14 @@ export function NodeConfigModal({ node, systems, onClose }: Props) {
           </div>
 
           <div>
-            <label className="block text-xs text-gray-400 mb-1">Node Type</label>
+            <label className="block text-xs text-gray-400 mb-1">Node Type *</label>
             <select
               value={nodeType}
               onChange={(e) => setNodeType(e.target.value)}
               className="w-full bg-gray-800 border border-gray-700 rounded-lg px-3 py-2 text-white text-sm focus:outline-none focus:border-indigo-500"
+              required
             >
+              <option value="">Select node type...</option>
               <option value="fixed">Fixed Node (Standard)</option>
               <option value="portable">Portable Node (Handheld)</option>
             </select>
@@ -138,7 +140,7 @@ export function NodeConfigModal({ node, systems, onClose }: Props) {
           <div className="flex gap-3 pt-1">
             <button
               type="submit"
-              disabled={saving || !systemId}
+              disabled={saving || !systemId || !nodeType}
               className="flex-1 bg-indigo-600 hover:bg-indigo-500 disabled:opacity-50 text-white rounded-lg py-2 text-sm font-semibold transition-colors"
             >
               {saving ? "Saving…" : "Assign & Configure"}