refactor: organize scripts/, remove stale root dirs, clean up structure

scripts/ reorganization:
- Sort 14 loose root scripts into subfolders:
  blockchain/ (genesis, proposer, mock chain, testnet BTC)
  dev/ (CLI wrapper, dev services, OpenAPI gen, systemd setup, domain proxy)
  ops/ (coordinator proxy, remote tunnel)
  gpu/ (miner workflow)
- Merge scripts/testing/ into scripts/test/ (eliminate duplicate folder)
- Create scripts/examples/ for usage demos and simulations

Root-level cleanup:
- Move home/ (12 simulation scripts) → scripts/examples/
- Move dev-utils/ (2 files) → scripts/dev/
- Move protocols/receipts/sample → tests/fixtures/
- Delete stale src/ (duplicate of apps/blockchain-node/src/)
- Remove empty home/, dev-utils/, protocols/ directories

Documentation updates:
- Update docs/6_architecture/8_codebase-structure.md tree and table
- Update root README.md tree to reflect new structure

scripts/dev/setup_systemd.sh

@@ -0,0 +1,49 @@
+#!/bin/bash
+
+# Setup AITBC Systemd Services
+echo "🔧 Setting up AITBC systemd services..."
+
+# Copy service files
+echo "📁 Copying service files..."
+sudo cp systemd/aitbc-*.service /etc/systemd/system/
+
+# Reload systemd daemon
+echo "🔄 Reloading systemd daemon..."
+sudo systemctl daemon-reload
+
+# Stop existing processes
+echo "⏹️ Stopping existing processes..."
+pkill -f "coordinator-api" || true
+pkill -f "simple_exchange_api.py" || true
+pkill -f "server.py --port 3002" || true
+pkill -f "wallet_daemon" || true
+pkill -f "node.main" || true
+
+# Enable services
+echo "✅ Enabling services..."
+sudo systemctl enable aitbc-coordinator-api.service
+sudo systemctl enable aitbc-exchange-api.service
+sudo systemctl enable aitbc-exchange-frontend.service
+sudo systemctl enable aitbc-wallet.service
+sudo systemctl enable aitbc-node.service
+
+# Start services
+echo "🚀 Starting services..."
+sudo systemctl start aitbc-coordinator-api.service
+sudo systemctl start aitbc-exchange-api.service
+sudo systemctl start aitbc-exchange-frontend.service
+sudo systemctl start aitbc-wallet.service
+sudo systemctl start aitbc-node.service
+
+# Check status
+echo ""
+echo "📊 Service Status:"
+for service in aitbc-coordinator-api aitbc-exchange-api aitbc-exchange-frontend aitbc-wallet aitbc-node; do
+    status=$(sudo systemctl is-active $service)
+    echo "  $service: $status"
+done
+
+echo ""
+echo "📝 To view logs: sudo journalctl -u <service-name> -f"
+echo "📝 To restart: sudo systemctl restart <service-name>"
+echo "📝 To stop: sudo systemctl stop <service-name>"