refactor: move tunnel and respond into core

packages/core/src/mcp/respond.ts

@@ -0,0 +1,13 @@
+import type { CallToolResult } from '@modelcontextprotocol/sdk/types.js'
+
+export const ok = (payload: unknown): CallToolResult => ({
+    content: [{ type: 'text', text: JSON.stringify(payload) }]
+})
+
+export const fail = (message: string): CallToolResult => ({
+    content: [{ type: 'text', text: message }],
+    isError: true
+})
+
+export const errorMessage = (error: unknown): string =>
+    error instanceof Error ? error.message : String(error)