chore(frontend): introduce prettier + eslint and prune unused code

- Add Prettier 3 with prettier-plugin-organize-imports (sorts/removes unused imports)
- Add ESLint 10 flat config with typescript-eslint + eslint-plugin-vue + eslint-config-prettier
- Add root scripts: format, format:check, lint, lint:fix
- Reformat 257 files across admin-web, ops-web, desktop-client, packages
- Remove unused locals/exports flagged by --noUnusedLocals/--noUnusedParameters
- Fix duplicate localTabLabel key, surrogate-pair regex u-flag, NBSP literal in regex
- Skip server/ (Go) and apps/browser-extension/ (deprecated per ADR)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/ops-web/src/App.vue

@@ -7,22 +7,22 @@
 </template>
 
 <script setup lang="ts">
-import { onMounted } from "vue";
+import { onMounted } from 'vue'
 
-import { useAuthStore } from "@/stores/auth";
+import { useAuthStore } from '@/stores/auth'
 
-const auth = useAuthStore();
+const auth = useAuthStore()
 
 const themeConfig = {
   token: {
-    colorPrimary: "#4f46e5",
-    colorLink: "#4f46e5",
-    colorInfo: "#4f46e5",
+    colorPrimary: '#4f46e5',
+    colorLink: '#4f46e5',
+    colorInfo: '#4f46e5',
     borderRadius: 6,
   },
-};
+}
 
 onMounted(() => {
-  if (!auth.initialized) auth.hydrate();
-});
+  if (!auth.initialized) auth.hydrate()
+})
 </script>