feat(mcp): add websearch_exa as built-in MCP

- Add src/mcp/ directory with websearch_exa configuration
- Configure Exa AI remote MCP (https://mcp.exa.ai/mcp)
- Export builtinMcps from plugin config
- Update documentation (EN/KO) with Built-in MCPs section

src/index.ts

@@ -3,6 +3,7 @@ import { builtinAgents } from "./agents"
 import { createTodoContinuationEnforcer, createContextWindowMonitorHook, createSessionRecoveryHook } from "./hooks"
 import { updateTerminalTitle } from "./features/terminal"
 import { builtinTools } from "./tools"
+import { builtinMcps } from "./mcp"
 
 const OhMyOpenCodePlugin: Plugin = async (ctx) => {
   const todoContinuationEnforcer = createTodoContinuationEnforcer(ctx)
@@ -27,6 +28,10 @@ const OhMyOpenCodePlugin: Plugin = async (ctx) => {
         ...config.tools,
         grep: false,
       }
+      config.mcp = {
+        ...config.mcp,
+        ...builtinMcps,
+      }
     },
 
     event: async (input) => {