change the MCP server build script to point at the custom binary

update package:ai in deps, add entrypoint script for the mcp server which injects an analytics instance

Change-Id: I1fd770a061085e7303c24b0c76e48d208687d9ad
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/437080
Auto-Submit: Jake Macdonald <jakemac@google.com>
Reviewed-by: Ben Konyi <bkonyi@google.com>
Commit-Queue: Ben Konyi <bkonyi@google.com>

utils/dart_mcp_server/BUILD.gn

@@ -13,12 +13,12 @@ group("dart_mcp_server_aot") {
 }
 
 aot_snapshot("dart_mcp_server_aot_snapshot") {
-  main_dart = "../../third_party/pkg/ai/pkgs/dart_mcp_server/bin/main.dart"
+  main_dart = "dart_mcp_server.dart"
   output = "$root_gen_dir/dart_mcp_server_aot.dart.snapshot"
 }
 
 aot_snapshot("dart_mcp_server_aot_product_snapshot") {
-  main_dart = "../../third_party/pkg/ai/pkgs/dart_mcp_server/bin/main.dart"
+  main_dart = "dart_mcp_server.dart"
   output = "$root_gen_dir/dart_mcp_server_aot_product.dart.snapshot"
 
   # dartaotruntime has dart_product_config applied to it,

utils/dart_mcp_server/dart_mcp_server.dart

@@ -0,0 +1,23 @@
+// Copyright (c) 2025, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// A custom entrypoint used by `dart mcp-server`. Injects an analytics instance
+/// using the [DashTool.dartTool] tool.
+library;
+
+import 'dart:io';
+
+import 'package:dart_mcp_server/dart_mcp_server.dart';
+import 'package:unified_analytics/unified_analytics.dart';
+
+void main(List<String> args) async {
+  exitCode = await DartMCPServer.run(
+    args,
+    analytics: Analytics(
+      tool: DashTool.dartTool,
+      // The actual version is part up to the first space.
+      dartVersion: Platform.version.split(' ').first,
+    ),
+  );
+}