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-blockchain-p2p.service

@@ -1,6 +1,6 @@
 [Unit]
 Description=AITBC Blockchain P2P Network Service
-After=network.target redis.service
+After=network.target
 
 [Service]
 Type=simple
@@ -10,7 +10,7 @@ WorkingDirectory=/opt/aitbc/apps/blockchain-node
 Environment=PATH=/usr/bin:/usr/local/bin:/usr/bin:/bin
 Environment=PYTHONPATH=/opt/aitbc/apps/blockchain-node/src:/opt/aitbc/apps/blockchain-node/scripts
 EnvironmentFile=/etc/aitbc/blockchain.env
-ExecStart=/opt/aitbc/venv/bin/python -m aitbc_chain.p2p_network --host ${p2p_bind_host} --port ${p2p_bind_port} --redis ${gossip_broadcast_url} --node-id ${proposer_id}
+ExecStart=/opt/aitbc/venv/bin/python -m aitbc_chain.p2p_network --host ${p2p_bind_host} --port ${p2p_bind_port} --peers ${p2p_peers} --node-id ${proposer_id}
 Restart=always
 RestartSec=5
 StandardOutput=journal