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/en/api-settings.json

@@ -167,6 +167,7 @@
     "enableContextCaching": "Enable context caching",
     "cacheTTL": "Cache TTL (minutes)",
     "cacheMaxSize": "Max Size (KB)",
+    "filePatterns": "Patterns",
     "autoCachePatterns": "Auto-cache patterns",
     "filePatternsHint": "Comma-separated glob patterns (e.g., *.md,*.ts)",
     "enabled": "Enabled",