fix(graph_rag): streamable-http transport + pin host ports >=5001

[lfnothias]

Two deploy fixes. 1) Enable the graph_rag server main over streamable-http (deploy.py launches each server via subprocess, so the entrypoint must serve; it was commented out, and graph_rag now runs on :5003 because of this). 2) Start host MCP port allocation at 5001 (start.sh, deploy.py) to avoid the macOS AirPlay Receiver on :5000.

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