fix(frontend): fix i18n and runtime error in EndpointList

Fix hardcoded English labels in cache strategy display and prevent runtime
error when filePatterns is undefined.

Changes:
- Replace hardcoded "TTL:", "Max:", "Patterns:" with formatMessage calls
- Add optional chaining for filePatterns.length to prevent undefined error
- Add "filePatterns" i18n key to en/zh api-settings.json

ccw/frontend/src/locales/zh/api-settings.json

@@ -164,6 +164,7 @@
     "enableContextCaching": "启用上下文缓存",
     "cacheTTL": "缓存 TTL（分钟）",
     "cacheMaxSize": "最大大小（KB）",
+    "filePatterns": "模式数",
     "autoCachePatterns": "自动缓存模式",
     "filePatternsHint": "逗号分隔的 glob 模式（例如：*.md,*.ts）",
     "enabled": "已启用",