refactor: migrate P2P network from Redis gossip to direct TCP mesh architecture

- Replaced Redis-based P2P with direct TCP connections for decentralized mesh networking
- Added handshake protocol with node_id exchange for peer authentication
- Implemented bidirectional connection management (inbound/outbound streams)
- Added peer dialing loop to continuously reconnect to initial peers
- Added ping/pong keepalive mechanism to maintain active connections
- Prevented duplicate connections through endpoint

systemd/aitbc-node.service

@@ -1,23 +0,0 @@
-[Unit]
-Description=AITBC Blockchain Node Service
-After=network.target
-Wants=network.target
-
-[Service]
-Type=simple
-User=root
-Group=root
-WorkingDirectory=/root/aitbc/apps/blockchain-node
-Environment=PATH=/usr/bin
-Environment=PYTHONPATH=/root/aitbc/apps/blockchain-node
-Environment=RUST_LOG=info
-ExecStart=/usr/bin/python3 -m node.main --datadir /root/aitbc/data --rpc-bind 0.0.0.0:8545
-ExecReload=/bin/kill -HUP $MAINPID
-Restart=always
-RestartSec=5
-StandardOutput=journal
-StandardError=journal
-SyslogIdentifier=aitbc-node
-
-[Install]
-WantedBy=multi-user.target