Fix PC installed-applications rendering; minor UI cleanups

The PC detail Installed Applications section 500d and vanished on any
real PC: ComputerInstalledApp had no to_dict, so the endpoint errored
and the v-if hid the section. Added the serializer (curated version
wins over the raw collected string, app name + description included)
and aligned PCDetail to the flat payload; regression test added.

Also: employee detail skips its USB panels when the usb plugin is
disabled (was firing 404s), and the shopfloor kiosk header is now
light-on-dark for readability.

810 tests pass; PC 259 installed apps verified live.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/views/ShopfloorDashboard.vue

@@ -444,7 +444,7 @@ function handlePhotoError(e) {
 .location-title {
   font-size: 18px;
   font-weight: 600;
-  color: #888;
+  color: #b8c4d8;
   text-transform: uppercase;
   letter-spacing: 2px;
 }
@@ -452,6 +452,7 @@ function handlePhotoError(e) {
 .header-center h1 {
   font-size: 28px;
   font-weight: 700;
+  color: #ffffff;
   text-transform: uppercase;
   letter-spacing: 2px;
   margin: 0;

frontend/src/views/employees/EmployeeDetail.vue

@@ -64,7 +64,7 @@
       </div>
 
       <!-- Currently Checked Out USB Devices -->
-      <div class="section-card">
+      <div v-if="usbEnabled" class="section-card">
         <h2 class="section-title">Checked Out USB Devices</h2>
         <div v-if="usbLoading" class="loading">Loading...</div>
         <div v-else-if="usbDevices.length === 0" class="empty">
@@ -99,7 +99,7 @@
       </div>
 
       <!-- USB Checkout History -->
-      <div class="section-card">
+      <div v-if="usbEnabled" class="section-card">
         <h2 class="section-title">USB Checkout History</h2>
         <div v-if="historyLoading" class="loading">Loading...</div>
         <div v-else-if="checkoutHistory.length === 0" class="empty">
@@ -136,6 +136,7 @@
 import { ref, computed, onMounted } from 'vue'
 import { useRoute } from 'vue-router'
 import { employeesApi, usbApi, notificationsApi } from '@/api'
+import { isPluginEnabled, loadEnabledPlugins } from '@/composables/enabledPlugins'
 import { useToast } from '../../composables/toast'
 const toast = useToast()
 
@@ -145,6 +146,7 @@ const employee = ref(null)
 const recognitions = ref([])
 const usbDevices = ref([])
 const checkoutHistory = ref([])
+const usbEnabled = ref(true)
 const loading = ref(true)
 const recognitionsLoading = ref(true)
 const usbLoading = ref(true)
@@ -175,7 +177,13 @@ const initials = computed(() => {
 
 onMounted(async () => {
   await loadEmployee()
-  await Promise.all([loadRecognitions(), loadUSBDevices(), loadCheckoutHistory()])
+  // Skip the USB panels entirely when the usb plugin is disabled - its
+  // /api/usb routes 404 otherwise and spam the console.
+  await loadEnabledPlugins()
+  usbEnabled.value = isPluginEnabled('usb')
+  const tasks = [loadRecognitions()]
+  if (usbEnabled.value) tasks.push(loadUSBDevices(), loadCheckoutHistory())
+  await Promise.all(tasks)
 })
 
 async function loadEmployee() {

frontend/src/views/pcs/PCDetail.vue

@@ -191,15 +191,15 @@
               <router-link
                 v-for="app in installedApps"
                 :key="app.id"
-                :to="`/applications/${app.application?.appid}`"
+                :to="`/applications/${app.appid}`"
                 class="app-item"
               >
                 <div class="app-info">
-                  <span class="app-name">{{ app.application?.appname }}</span>
-                  <span class="app-version" v-if="app.version">v{{ app.version }}</span>
+                  <span class="app-name">{{ app.appname }}</span>
+                  <span class="app-version" v-if="app.installedversion">v{{ app.installedversion }}</span>
                 </div>
-                <div class="app-desc" v-if="app.application?.appdescription">
-                  {{ app.application.appdescription }}
+                <div class="app-desc" v-if="app.appdescription">
+                  {{ app.appdescription }}
                 </div>
               </router-link>
             </div>