docs: restructure website, optimize HTML, gitignore private files

Website docs (website/docs/):
- Delete 6 stale -md.html duplicates
- Rename docs-clients/miners/developers → clients/miners/developers.html
- Unify header/nav across all 15 pages (new .site-header pattern)
- Fix 34 dead href=# links with real targets
- Upgrade Font Awesome v4→v6 in index.html
- Replace search stub with live client-side search (15-page index)
- Extract all inline CSS into shared docs.css (+630 lines)
- Extract inline theme JS into shared theme.js
- Strip inline style= attributes from 10+ pages
- Add .announce-banner, .source-links, .search-results CSS classes
- Add Markdown Source links to clients/miners/developers pages
- Update components.html title to Architecture & Components
- Move browser-wallet.html to website/wallet/, leave redirect
- Update all dates to February 2026

Website root:
- Delete 6 root-level duplicate HTML files (160KB saved)
- Rewire index.html and 404.html links

Root README.md:
- Fix 8 broken doc links to new numbered folder structure
- Update copyright to 2026

.gitignore + .example files:
- Gitignore private files: .aitbc.yaml, .env, deploy scripts,
  GPU scripts, service scripts, infra configs, .windsurf/, website README
- Create 7 .example files for GitHub users with sanitized templates
- Untrack 47 previously committed private files

Live server:
- Push all website files to aitbc-cascade:/var/www/html/
- Clean stale admin.html and index.nginx-debian.html

scripts/deploy/setup-gossip-relay.sh

@@ -1,113 +0,0 @@
-#!/bin/bash
-
-# Setup gossip relay to connect blockchain nodes
-
-set -e
-
-echo "🌐 Setting up Gossip Relay for Blockchain Nodes"
-echo "=============================================="
-
-# Colors
-GREEN='\033[0;32m'
-YELLOW='\033[1;33m'
-NC='\033[0m'
-
-print_status() {
-    echo -e "${GREEN}[INFO]${NC} $1"
-}
-
-print_warning() {
-    echo -e "${YELLOW}[WARN]${NC} $1"
-}
-
-# Stop existing nodes
-print_status "Stopping blockchain nodes..."
-sudo systemctl stop blockchain-node blockchain-node-2 blockchain-rpc blockchain-rpc-2 2>/dev/null || true
-
-# Update node configurations to use broadcast backend
-print_status "Updating Node 1 configuration..."
-sudo cat > /opt/blockchain-node/.env << EOF
-CHAIN_ID=ait-devnet
-DB_PATH=./data/chain.db
-RPC_BIND_HOST=127.0.0.1
-RPC_BIND_PORT=8082
-P2P_BIND_HOST=0.0.0.0
-P2P_BIND_PORT=7070
-PROPOSER_KEY=node1_proposer_key_$(date +%s)
-MINT_PER_UNIT=1000
-COORDINATOR_RATIO=0.05
-GOSSIP_BACKEND=broadcast
-GOSSIP_BROADCAST_URL=http://127.0.0.1:7070/gossip
-EOF
-
-print_status "Updating Node 2 configuration..."
-sudo cat > /opt/blockchain-node-2/.env << EOF
-CHAIN_ID=ait-devnet
-DB_PATH=./data/chain2.db
-RPC_BIND_HOST=127.0.0.1
-RPC_BIND_PORT=8081
-P2P_BIND_HOST=0.0.0.0
-P2P_BIND_PORT=7071
-PROPOSER_KEY=node2_proposer_key_$(date +%s)
-MINT_PER_UNIT=1000
-COORDINATOR_RATIO=0.05
-GOSSIP_BACKEND=broadcast
-GOSSIP_BROADCAST_URL=http://127.0.0.1:7070/gossip
-EOF
-
-# Create gossip relay service
-print_status "Creating gossip relay service..."
-sudo cat > /etc/systemd/system/blockchain-gossip-relay.service << EOF
-[Unit]
-Description=AITBC Blockchain Gossip Relay
-After=network.target
-
-[Service]
-Type=exec
-User=root
-WorkingDirectory=/opt/blockchain-node
-Environment=PATH=/opt/blockchain-node/.venv/bin:/usr/local/bin:/usr/bin:/bin
-Environment=PYTHONPATH=/opt/blockchain-node/src:/opt/blockchain-node/scripts
-ExecStart=/opt/blockchain-node/.venv/bin/python3 -m aitbc_chain.gossip.relay --port 7070 --host 0.0.0.0
-Restart=always
-RestartSec=5
-
-[Install]
-WantedBy=multi-user.target
-EOF
-
-# Enable and start gossip relay
-print_status "Starting gossip relay..."
-sudo systemctl daemon-reload
-sudo systemctl enable blockchain-gossip-relay
-sudo systemctl start blockchain-gossip-relay
-
-# Wait for relay to start
-sleep 2
-
-# Check if relay is running
-print_status "Checking gossip relay status..."
-sudo systemctl status blockchain-gossip-relay --no-pager | head -10
-
-# Restart blockchain nodes
-print_status "Restarting blockchain nodes with shared gossip..."
-sudo systemctl start blockchain-node blockchain-node-2 blockchain-rpc blockchain-rpc-2
-
-# Wait for nodes to start
-sleep 3
-
-# Check status
-print_status "Checking node status..."
-sudo systemctl status blockchain-node blockchain-node-2 --no-pager | grep -E 'Active:|Main PID:'
-
-echo ""
-print_status "✅ Gossip relay setup complete!"
-echo ""
-echo "Nodes are now connected via shared gossip backend."
-echo "They should sync blocks and transactions."
-echo ""
-echo "To verify connectivity:"
-echo "  1. Run: python /opt/test_blockchain_simple.py"
-echo "  2. Check if heights are converging"
-echo ""
-echo "Gossip relay logs: sudo journalctl -u blockchain-gossip-relay -f"