feat(mcp): add package-backed ast-grep MCP

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

packages/ast-grep-mcp/src/process-output-timeout.ts

@@ -0,0 +1,28 @@
+type SpawnedProcess = {
+	stdout: ReadableStream | null
+	stderr: ReadableStream | null
+	exited: Promise<number>
+	kill: () => void
+}
+
+export async function collectProcessOutputWithTimeout(
+	process: SpawnedProcess,
+	timeoutMs: number
+): Promise<{ stdout: string; stderr: string; exitCode: number }> {
+	const timeoutPromise = new Promise<never>((_, reject) => {
+		const timeoutId = setTimeout(() => {
+			process.kill()
+			reject(new Error(`Search timeout after ${timeoutMs}ms`))
+		}, timeoutMs)
+		process.exited.then(() => clearTimeout(timeoutId))
+	})
+
+	const stdoutPromise = process.stdout ? new Response(process.stdout).text() : Promise.resolve("")
+	const stderrPromise = process.stderr ? new Response(process.stderr).text() : Promise.resolve("")
+
+	const stdout = await Promise.race([stdoutPromise, timeoutPromise])
+	const stderr = await stderrPromise
+	const exitCode = await process.exited
+
+	return { stdout, stderr, exitCode }
+}