feat(i18n): add German (de) locale

Adds a complete German translation covering all 4 735 UI strings.

New files:
- packages/ui/src/lib/i18n/messages/de.ts
- packages/ui/src/lib/i18n/messages/de.settings.ts

Modified files:
- runtime.ts: add 'de' to Locale type, LOCALES array, LOCALE_LABEL_KEYS
- store.ts: add 'de' case in loadDictionary
- messages/en.ts: add common.language.german key

packages/ui/src/lib/i18n/messages/en.ts

@@ -5,6 +5,7 @@ export const dict = {
   'common.loading': 'Loading...',
   'common.unavailable': 'Unavailable',
   'common.language.english': 'English',
+  'common.language.german': 'German',
   'common.language.french': 'French',
   'common.language.simplifiedChinese': 'Chinese (Simplified)',
   'common.language.traditionalChinese': 'Chinese (Traditional)',

packages/ui/src/lib/i18n/runtime.ts

@@ -1,6 +1,6 @@
-export type Locale = 'en' | 'fr' | 'zh-CN' | 'zh-TW' | 'uk' | 'es' | 'pt-BR' | 'ko' | 'pl' | 'ja';
+export type Locale = 'en' | 'de' | 'fr' | 'zh-CN' | 'zh-TW' | 'uk' | 'es' | 'pt-BR' | 'ko' | 'pl' | 'ja';
 
-export const LOCALES = ['en', 'fr', 'zh-CN', 'zh-TW', 'uk', 'es', 'pt-BR', 'ko', 'pl', 'ja'] as const satisfies readonly Locale[];
+export const LOCALES = ['en', 'de', 'fr', 'zh-CN', 'zh-TW', 'uk', 'es', 'pt-BR', 'ko', 'pl', 'ja'] as const satisfies readonly Locale[];
 
 export const DEFAULT_LOCALE: Locale = 'en';
 
@@ -14,6 +14,7 @@ export const LOCALE_LABEL_KEYS: Record<Locale, 'common.language.english' | 'comm
   'pt-BR': 'common.language.brazilianPortuguese',
   ko: 'common.language.korean',
   pl: 'common.language.polish',
+  de: 'common.language.german',
   ja: 'common.language.japanese',
 };
 

packages/ui/src/lib/i18n/store.ts

@@ -42,7 +42,9 @@ async function loadDictionary(locale: Locale): Promise<I18nDictionary> {
               ? await import('./messages/ko') as { dict: I18nDictionary }
               : locale === 'pl'
                 ? await import('./messages/pl') as { dict: I18nDictionary }
-                : locale === 'ja'
+                : locale === 'de'
+      ? await import('./messages/de') as { dict: I18nDictionary }
+      : locale === 'ja'
                   ? await import('./messages/ja') as { dict: I18nDictionary }
                   : { dict: enDict };
   dictionaries.set(locale, mod.dict);