feat: Implement extension and bot limitations across services and UI (#1991)

- Added checks for maximum allowed extensions, bots, and pipelines in the backend services (PluginsRouterGroup, BotService, MCPService, PipelineService).
- Updated system configuration to include limitation settings for max_bots, max_pipelines, and max_extensions.
- Enhanced frontend components to handle limitations, providing user feedback when limits are reached.
- Added internationalization support for limitation messages in English, Japanese, Simplified Chinese, and Traditional Chinese.

web/src/i18n/locales/en-US.ts

@@ -962,6 +962,14 @@ const enUS = {
       sessions: 'Sessions',
     },
   },
+  limitation: {
+    maxBotsReached:
+      'Maximum number of bots ({{max}}) reached. Please remove an existing bot before creating a new one.',
+    maxPipelinesReached:
+      'Maximum number of pipelines ({{max}}) reached. Please remove an existing pipeline before creating a new one.',
+    maxExtensionsReached:
+      'Maximum number of extensions ({{max}}) reached. Please remove an existing MCP server or plugin before adding a new one.',
+  },
 };
 
 export default enUS;