fix(i18n): add missing translations for selectAll and theme toggle

- Add common.selectAll and common.items translations
- Add theme.light and theme.dark translations
- Update ab-mobile-nav to use i18n for theme toggle label
- Remove hardcoded fallback in ab-data-list

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

webui/src/components/basic/ab-data-list.vue

@@ -75,9 +75,9 @@ defineExpose({ selectedKeys, toggleSelectAll });
           :indeterminate="selectedKeys.size > 0 && selectedKeys.size < items.length"
           @change="toggleSelectAll"
         />
-        <span>{{ $t('common.selectAll') || 'Select All' }}</span>
+        <span>{{ $t('common.selectAll') }}</span>
       </label>
-      <span class="ab-data-list__count">{{ items.length }} items</span>
+      <span class="ab-data-list__count">{{ items.length }} {{ $t('common.items') }}</span>
     </div>
 
     <!-- Items -->

webui/src/components/layout/ab-mobile-nav.vue

@@ -55,7 +55,7 @@ const visibleItems = computed(() => navItems.filter((i) => !i.hidden));
     >
       <Moon v-if="!isDark" :size="18" class="mobile-nav__icon" />
       <Sun v-else :size="18" class="mobile-nav__icon" />
-      <span class="mobile-nav__label">{{ isDark ? 'Light' : 'Dark' }}</span>
+      <span class="mobile-nav__label">{{ isDark ? t('theme.light') : t('theme.dark') }}</span>
     </button>
   </nav>
 </template>

webui/src/i18n/en.json

@@ -352,7 +352,13 @@
   "common": {
     "cancel": "Cancel",
     "confirm": "Confirm",
-    "select": "Select"
+    "select": "Select",
+    "selectAll": "Select All",
+    "items": "items"
+  },
+  "theme": {
+    "light": "Light",
+    "dark": "Dark"
   },
   "offset": {
     "dialog_title": "Season/Episode Mismatch Detected",

webui/src/i18n/zh-CN.json

@@ -352,7 +352,13 @@
   "common": {
     "cancel": "取消",
     "confirm": "确认",
-    "select": "选择"
+    "select": "选择",
+    "selectAll": "全选",
+    "items": "项"
+  },
+  "theme": {
+    "light": "浅色",
+    "dark": "深色"
   },
   "offset": {
     "dialog_title": "检测到季度/集数不匹配",