feat(ui): restyle DeviceSelect with Popover, Icon, and Slate tokens

Also add a `declare module "feather-icons"` ambient shim in
desktop/src/vite-env.d.ts: Icon.vue (Task 6) imports the untyped
feather-icons package, and DeviceSelect is the first production
component to pull Icon.vue into vue-tsc's reachable graph, which
surfaced a pre-existing missing type declaration that broke
`npm run build`.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

desktop/src/vite-env.d.ts

@@ -5,3 +5,5 @@ declare module "*.vue" {
   const component: DefineComponent<{}, {}, any>;
   export default component;
 }
+
+declare module "feather-icons";

n-link-core/components/DeviceSelect.vue

@@ -1,55 +1,53 @@
 <template>
-  <div class="header border-b px-2 py-2 flex w-full">
+  <div class="header border-b border-edge px-2 py-2 flex w-full bg-raised">
-    <button @click="$devices.enumerate()" class="flex-shrink-0 mr-2 focus:outline-none"
+    <button @click="$devices.enumerate()" class="flex-shrink-0 mr-2 focus:outline-none text-fg"
             :class="$devices.enumerating && 'cursor-not-allowed opacity-25'" :disabled="$devices.enumerating">
-      <img :src="refreshCw" class="w-5"/>
+      <icon name="refresh-cw" :size="20"/>
       <div v-if="scanHint && Object.keys($devices.devices).length === 0" class="p-4 refresh-popup">
         Click to connect a device
       </div>
     </button>
-    <el-popover width="239" :show-arrow="false" popper-class="focus:outline-none dev-select-pop" v-model:visible="active"
+    <popover v-model:visible="active" :width="239" class="w-full">
-                class="w-full overflow-hidden">
+      <template #trigger>
-      <template #reference>
         <div class="relative w-full focus:outline-none">
-          <div
+          <div class="block w-full bg-surface border border-edge hover:border-muted px-4 py-3/2 pr-8
-              class="block w-full bg-white border border-gray-400 hover:border-gray-500 px-4 py-3/2 pr-8 rounded shadow leading-tight focus:outline-none focus:shadow-outline h-8 truncate">
+                      rounded leading-tight focus:outline-none h-8 truncate text-fg">
             <span v-if="selectedCalculator">
               <small class="tabular-nums">{{ selectedCalculator }}</small>
               <span v-if="calc && calc.info"> {{ calc.info.name }}</span>
               <span v-else> {{ calc!.name }}</span>
             </span>
-            <span v-else class="text-gray-700 text-sm">
+            <span v-else class="text-muted text-sm">
               Select a device...
             </span>
           </div>
-          <div class="pointer-events-none absolute inset-y-0 right-0 flex items-center px-2 text-gray-700">
+          <div class="pointer-events-none absolute inset-y-0 right-0 flex items-center px-2 text-muted">
             <svg class="fill-current h-4 w-4" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 20 20">
               <path d="M9.293 12.95l.707.707L15.657 8l-1.414-1.414L10 10.828 5.757 6.586 4.343 8z"/>
             </svg>
           </div>
         </div>
       </template>
-      <ul>
+      <ul class="-m-3">
         <li v-for="(device, id) in $devices.devices" :key="id"
-            class="p-2 hover:bg-blue-500 hover:text-white w-full cursor-pointer" @click="select(id)">
+            class="p-2 hover:bg-accent hover:text-accent-fg w-full cursor-pointer text-fg" @click="select(id)">
           <small class="tabular-nums">{{ id }}</small>
           <span v-if="device.info"> {{ device.info.name }}</span>
           <span v-else> {{ device.name }}</span>
         </li>
-        <div v-if="!anyCalcs" class="p-2 w-full">
+        <div v-if="!anyCalcs" class="p-2 w-full text-muted">
           No calculators found
         </div>
       </ul>
-    </el-popover>
+    </popover>
   </div>
 </template>
 
 <script setup lang="ts">
 import {computed, inject, ref} from 'vue';
-import {ElPopover} from 'element-plus';
-import 'element-plus/es/components/popover/style/css';
 import {DEVICES_KEY, type GenericDevices} from './devices';
-import refreshCw from 'feather-icons/dist/icons/refresh-cw.svg';
+import Popover from './Popover.vue';
+import Icon from './Icon.vue';
 
 withDefaults(defineProps<{
   scanHint?: boolean;
@@ -86,7 +84,7 @@ const anyCalcs = computed(() => !!Object.keys(devices.devices).length);
   $size: 9px;
   margin-left: -4.5px;
   margin-top: 10px;
-  @apply absolute bg-blue-600 text-white;
+  @apply absolute bg-accent text-accent-fg;
   &:before {
     content: "";
     position: absolute;
@@ -94,16 +92,8 @@ const anyCalcs = computed(() => !!Object.keys(devices.devices).length);
     top: $size * -2;
     border-top: $size solid transparent;
     border-right: $size solid transparent;
-    border-bottom: $size solid theme('colors.blue.600');
+    border-bottom: $size solid var(--accent);
-
     border-left: $size solid transparent;
   }
 }
 </style>
-
-<style lang="scss">
-.dev-select-pop {
-  margin-top: 0 !important;
-  @apply p-0 overflow-hidden;
-}
-</style>