docs(hive): add Codex MCP integration example

[wForget]

Summary

The Hive connector can run independently as an MCP server and integrate directly with Codex, without starting the Analytics Agent application.

This PR adds an example showing how to:

• Register the Hive connector in Codex using mcp_servers
• Launch the connector locally with uv run --project
• Connect to Apache Kyuubi
• Configure Kerberos authentication through MCP environment variables

[shirshanka]

Thanks @wForget — nice addition, and a good showcase of the connectors running standalone as MCP servers. 🙏

Verified against the connector code:

• The console script analytics-agent-connector-hive matches connectors/hive/pyproject.toml ([project.scripts] → analytics_agent_connector_hive.server:main). ✓
• Every env var in the example (HIVE_DATABASE, HIVE_HOST, HIVE_PORT, HIVE_AUTH, HIVE_KERBEROS_SERVICE_NAME) matches what server.py actually reads. ✓
• The KERBEROS example correctly omits HIVE_USER/HIVE_PASSWORD (those are for the LDAP/PLAIN paths).

Accurate and self-contained — approving. 🎉