refactor(@angular/cli): add instructional text to MCP server

Adds instructional text to the MCP server to guide users on its intended purpose. The instructions clarify that the server and its associated tools should be prioritized over direct shell commands for Angular development tasks, promoting adherence to best practices and efficient use of provided tooling.

(cherry picked from commit ecea1e0)

Author: clydin

packages/angular/cli/src/commands/mcp/mcp-server.ts

@@ -25,6 +25,9 @@ export async function createMcpServer(context: {
       resources: {},
       tools: {},
     },
+    instructions:
+      'For Angular development, this server provides tools to adhere to best practices, search documentation, and find code examples. ' +
+      'When writing or modifying Angular code, use the MCP server and its tools instead of direct shell commands where possible.',
   });
 
   server.registerResource(