refactor(ansible): rename freecad_mcp env vars and rework deployment

- Drop `FREECAD_MCP_` prefix from env vars (use `FREECAD_*`)
- Update freecad_mcp port from 22032 to 22061
- Document that FreeCAD bridge is required for tool calls
- Replace kottos deployment with pallas deployment

ansible/freecad_mcp/freecad-mcp-bridge.service.j2

@@ -0,0 +1,21 @@
+[Unit]
+Description=FreeCAD MCP XML-RPC Bridge (GUI)
+After=network.target
+
+[Service]
+Type=simple
+User={{ principal_user }}
+WorkingDirectory={{ freecad_mcp_bridge_directory }}
+Environment=DISPLAY={{ freecad_mcp_bridge_display }}
+Environment=XAUTHORITY=/home/{{ principal_user }}/.Xauthority
+Environment=FREECAD_XMLRPC_PORT={{ freecad_mcp_xmlrpc_port | default('9875') }}
+Environment=FREECAD_SOCKET_PORT={{ freecad_mcp_socket_port | default('9876') }}
+ExecStart=/usr/bin/freecad {{ freecad_mcp_bridge_directory }}/freecad/RobustMCPBridge/freecad_mcp_bridge/startup_bridge.py
+Restart=on-failure
+RestartSec=10
+StandardOutput=journal
+StandardError=journal
+SyslogIdentifier=freecad-mcp-bridge
+
+[Install]
+WantedBy=multi-user.target