Add stdio entrypoint so server can be launched directly

[danilobrando]

Summary

server.py defines the FastMCP instance and 29 tools, but has no __main__ block — running python3 server.py loads the module without starting the server. Claude Code (and any MCP client following the README) reports Failed to connect.

Repro

git clone https://github.com/adelaidasofia/substack-mcp
cd substack-mcp
pip3 install -r requirements.txt
# Register in .mcp.json:
#   "substack": { "command": "python3", "args": ["/path/to/server.py"] }
claude mcp list
# substack: ... - ✗ Failed to connect

Sending an MCP initialize JSON-RPC over stdio also returns no response — the process exits as soon as stdin closes because nothing is reading from it.

Fix

Add the standard FastMCP stdio entrypoint at the end of server.py:

if __name__ == "__main__":
    mcp.run(transport="stdio", show_banner=False)

show_banner=False keeps stdout clean for the MCP protocol (FastMCP prints to stderr by default, but the banner can leak into stdout in some setups).

Verified

After the patch:

$ claude mcp list
substack: ... - ✓ Connected

And test_connection returns the expected profile payload over the live MCP transport.