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/admin-web/src/components/ImageUploadProgressOverlay.vue

@@ -1,18 +1,18 @@
 <script setup lang="ts">
-import { computed } from "vue";
-import { useI18n } from "vue-i18n";
+import { computed } from 'vue'
+import { useI18n } from 'vue-i18n'
 
-import { useImageUploadProgress } from "@/lib/image-webp";
+import { useImageUploadProgress } from '@/lib/image-webp'
 
-const { t } = useI18n();
-const progress = useImageUploadProgress();
+const { t } = useI18n()
+const progress = useImageUploadProgress()
 
 const stageLabel = computed(() => {
   if (!progress.visible) {
-    return "";
+    return ''
   }
-  return t(`common.imageUploadProgress.stages.${progress.stage}`);
-});
+  return t(`common.imageUploadProgress.stages.${progress.stage}`)
+})
 </script>
 
 <template>
@@ -21,7 +21,7 @@ const stageLabel = computed(() => {
       <div v-if="progress.visible" class="image-upload-progress">
         <div class="image-upload-progress__card">
           <div class="image-upload-progress__header">
-            <strong>{{ t("common.imageUploadProgress.title") }}</strong>
+            <strong>{{ t('common.imageUploadProgress.title') }}</strong>
             <span>{{ progress.percent }}%</span>
           </div>
           <div class="image-upload-progress__file" :title="progress.fileName">