feat: auto-assign extensions + form validation

- Backend: new customers auto-get all active extensions assigned
- Frontend: required field validation (name, URL, credentials)
- Frontend: removed manual "add extension" dropdown (auto-assigned)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

dashboard/src/App.jsx

@@ -179,7 +179,13 @@ function CustomerForm({ onDone, onCancel, customer }) {
     }
   }
 
+  const [error, setError] = useState('')
+
   const submit = async () => {
+    if (!form.name.trim()) { setError('שם לקוח הוא שדה חובה'); return }
+    if (!form.espocrm_url.trim()) { setError('EspoCRM URL הוא שדה חובה'); return }
+    if (!isEdit && !form.espocrm_api_key) { setError('יש להזין שם משתמש וסיסמה'); return }
+    setError('')
     const payload = { ...form }
     if (!payload.espocrm_api_key) delete payload.espocrm_api_key
     const url = isEdit ? `${API}/customers/${customer.id}` : `${API}/customers`
@@ -223,6 +229,7 @@ function CustomerForm({ onDone, onCancel, customer }) {
           <p className="text-[10px] text-slate-400 text-right">השאר ריק כדי לא לשנות</p>
         )}
       </div>
+      {error && <p className="text-xs text-red-600 font-bold text-right">{error}</p>}
       <div className="flex gap-2">
         <button onClick={submit}
           className="deep-action-gradient text-white px-4 py-2.5 rounded-xl font-bold flex-1 shadow-lg shadow-blue-500/20 active:scale-95 transition-all">
@@ -504,16 +511,7 @@ function CustomerDetail({ customerId, onDelete }) {
         </table>
       </section>
 
-      {available.length > 0 && (
-        <div className="mt-6 bg-white rounded-xl p-6">
-          <h4 className="text-sm font-bold text-slate-400 uppercase tracking-widest mb-3">הוסף הרחבה</h4>
-          <select onChange={e => e.target.value && assign(parseInt(e.target.value))}
-            className="bg-slate-50 border-none rounded-xl px-4 py-2.5 w-full text-sm focus:ring-2 focus:ring-blue-500">
-            <option value="">בחר הרחבה...</option>
-            {available.map(e => <option key={e.id} value={e.id}>{e.name} v{e.latest_version}</option>)}
-          </select>
-        </div>
-      )}
+      {/* Extensions are auto-assigned on customer creation */}
     </div>
   )
 }