fix:거래처 수정 시 null 값 input 경고 해결

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

resources/views/finance/partners.blade.php

@@ -108,7 +108,14 @@ function PartnersManagement() {
     });
 
     const handleAdd = () => { setModalMode('add'); setFormData(initialFormState); setShowModal(true); };
-    const handleEdit = (item) => { setModalMode('edit'); setEditingItem(item); setFormData({ ...item }); setShowModal(true); };
+    const handleEdit = (item) => {
+        setModalMode('edit');
+        setEditingItem(item);
+        const safeItem = {};
+        Object.keys(initialFormState).forEach(key => { safeItem[key] = item[key] ?? ''; });
+        setFormData(safeItem);
+        setShowModal(true);
+    };
     const handleSave = async () => {
         if (!formData.name) { alert('거래처명을 입력해주세요.'); return; }
         setSaving(true);