fix: polish form validation and feedback across views

- Server.vue: Add loading/disabled state to WiFi connect button,
  success toast on WiFi connection
- Credentials.vue: Disable verify button when input empty, add
  disabled styles

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

neode-ui/src/views/Server.vue

@@ -385,8 +385,8 @@
           />
           <p v-if="wifiError" class="text-sm text-red-400 mb-3">{{ wifiError }}</p>
           <div class="flex gap-2">
-            <button @click="wifiConnecting = false; wifiPassword = ''; wifiError = ''" class="flex-1 px-3 py-2 glass-button rounded-lg text-sm">Cancel</button>
-            <button @click="connectToWifi" class="flex-1 px-3 py-2 glass-button rounded-lg text-sm font-medium" :disabled="!wifiPassword">Connect</button>
+            <button @click="wifiConnecting = false; wifiPassword = ''; wifiError = ''" :disabled="wifiSubmitting" class="flex-1 px-3 py-2 glass-button rounded-lg text-sm">Cancel</button>
+            <button @click="connectToWifi" class="flex-1 px-3 py-2 glass-button rounded-lg text-sm font-medium disabled:opacity-50 disabled:cursor-not-allowed" :disabled="!wifiPassword || wifiSubmitting">{{ wifiSubmitting ? 'Connecting...' : 'Connect' }}</button>
           </div>
         </div>
       </div>
@@ -583,6 +583,7 @@ const showWifiModal = ref(false)
 const wifiScanning = ref(false)
 const wifiNetworks = ref<WifiNetwork[]>([])
 const wifiConnecting = ref(false)
+const wifiSubmitting = ref(false)
 const wifiSelectedSsid = ref('')
 const wifiPassword = ref('')
 const wifiError = ref('')
@@ -676,15 +677,20 @@ function selectWifi(ssid: string) {
 async function connectToWifi() {
   if (!wifiPassword.value || !wifiSelectedSsid.value) return
   wifiError.value = ''
+  wifiSubmitting.value = true
   try {
     await rpcClient.call({ method: 'network.configure-wifi', params: { ssid: wifiSelectedSsid.value, password: wifiPassword.value } })
     showWifiModal.value = false
     wifiConnecting.value = false
     wifiPassword.value = ''
+    logsToast.value = 'WiFi connected successfully'
+    setTimeout(() => { logsToast.value = '' }, 4000)
     loadInterfaces()
   } catch (e) {
     wifiError.value = e instanceof Error ? e.message : 'WiFi connection failed. Check password and try again.'
     if (import.meta.env.DEV) console.warn('WiFi connection failed', e)
+  } finally {
+    wifiSubmitting.value = false
   }
 }