Build Routes tab with paginated list and Zod-validated API responses

Routes tab (Phase 3.1):
- Paginated FlatList fetching from Journal REST API
- Route cards with name, distance (km), elevation gain, day count
- Pull-to-refresh, loading spinner, error state with retry, empty state
- Safe area insets for notch and tab bar

API client:
- Import types from @trails-cool/api instead of hand-written interfaces
- Parse list/detail responses through Zod schemas at runtime
- Add zod as mobile app dependency

i18n:
- Add mobile namespace (en + de) for routes, activities, profile, login

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

pnpm-lock.yaml

@@ -336,6 +336,9 @@ importers:
       react-native-screens:
         specifier: ~4.23.0
         version: 4.23.0(react-native@0.83.4(@babel/core@7.29.0)(@types/react@19.2.14)(react@19.2.0))(react@19.2.0)
+      zod:
+        specifier: ^3.25.76
+        version: 3.25.76
     devDependencies:
       '@testing-library/react-native':
         specifier: ^13.3.3