Add German (de) locale + broadcast-not-translated tooltip

frontend/src/components/layout/AppLayout.vue

@@ -149,14 +149,18 @@ onUnmounted(() => {
       </nav>
 
       <div class="sidebar-footer">
-        <!-- Language switcher -->
+        <!-- Language switcher. The :title on both variants surfaces a hint
+             that in-game broadcast messages (vote-thanks, restart warnings,
+             etc.) stay in whatever language they were saved in — switching
+             panel language only translates the panel UI itself. -->
         <div class="lang-switcher" v-if="!sidebarCollapsed">
           <Select
             v-model="selectedLocale"
             :options="localeOptions"
             optionLabel="label"
             optionValue="value"
             class="lang-select"
+            :title="t('layout.broadcastsHint')"
           />
         </div>
         <Button
@@ -167,7 +171,7 @@ onUnmounted(() => {
           severity="secondary"
           @click="cycleLocale"
           class="lang-cycle-btn"
-          :title="SUPPORTED_LOCALES[localeIndex]?.name"
+          :title="`${SUPPORTED_LOCALES[localeIndex]?.name} — ${t('layout.broadcastsHint')}`"
         />
 
         <!-- Connection indicator -->

frontend/src/i18n/index.ts

@@ -1,12 +1,14 @@
 import { createI18n } from 'vue-i18n'
 import en from './locales/en'
+import de from './locales/de'
 import zhCN from './locales/zh-CN'
 import zhTW from './locales/zh-TW'
 import ja from './locales/ja'
 import ko from './locales/ko'
 
 export const SUPPORTED_LOCALES = [
   { code: 'en', name: 'English' },
+  { code: 'de', name: 'Deutsch' },
   { code: 'zh-CN', name: '简体中文' },
   { code: 'zh-TW', name: '繁體中文' },
   { code: 'ja', name: '日本語' },
@@ -27,6 +29,7 @@ function getSavedLocale(): LocaleCode {
   }
   if (browserLang.startsWith('ja')) return 'ja'
   if (browserLang.startsWith('ko')) return 'ko'
+  if (browserLang.startsWith('de')) return 'de'
   return 'en'
 }
 
@@ -36,6 +39,7 @@ const i18n = createI18n({
   fallbackLocale: 'en',
   messages: {
     en,
+    de,
     'zh-CN': zhCN,
     'zh-TW': zhTW,
     ja,