feat(mcp): add Model Context Protocol integration

Add  MCP integration including:
- New MCP settings tab with server configuration
- Tool invocation UI components
- API endpoints for MCP management
- Integration with chat system for tool execution
- Example configurations

app/utils/constants.ts

@@ -8,6 +8,13 @@ export const MODEL_REGEX = /^\[Model: (.*?)\]\n\n/;
 export const PROVIDER_REGEX = /\[Provider: (.*?)\]\n\n/;
 export const DEFAULT_MODEL = 'claude-3-5-sonnet-latest';
 export const PROMPT_COOKIE_KEY = 'cachedPrompt';
+export const TOOL_EXECUTION_APPROVAL = {
+  APPROVE: 'Yes, approved.',
+  REJECT: 'No, rejected.',
+} as const;
+export const TOOL_NO_EXECUTE_FUNCTION = 'Error: No execute function found on tool';
+export const TOOL_EXECUTION_DENIED = 'Error: User denied access to tool execution';
+export const TOOL_EXECUTION_ERROR = 'Error: An error occured while calling tool';
 
 const llmManager = LLMManager.getInstance(import.meta.env);