[Example] Add MCP server example for AI agent integration #302

Motivation

The examples/ directory shows basic producer/consumer, async, and RPC patterns, but there is no example demonstrating integration with AI agents.

The Model Context Protocol (MCP) is the emerging standard for connecting AI tools (Cursor, Claude Desktop, Windsurf, etc.) to external data sources. An MCP server example would allow developers to interact with Pulsar topics through natural language, bridging messaging infrastructure and the AI agent ecosystem.

Proposed Change

Add examples/mcp_server.py that exposes three tools via the official MCP Python SDK (pip install mcp):

The example is a standalone script—mcp is only required at runtime for this example and is not added to the project's setup.py dependencies.

Configuration

Once configured in an MCP-compatible client (e.g. Cursor ~/.cursor/mcp.json), users can produce and consume Pulsar messages through natural language.

{
  "mcpServers": {
    "pulsar": {
      "command": "python3",
      "args": ["examples/mcp_server.py"],
      "env": {
        "PULSAR_BROKER_URL": "pulsar://localhost:6650"
      }
    }
  }
}

I'm happy to submit a PR for this.