feat: phantom trade auto-closure system

- Auto-close phantom positions immediately via market order
- Return HTTP 200 (not 500) to allow n8n workflow continuation
- Save phantom trades to database with full P&L tracking
- Exit reason: 'manual' category for phantom auto-closes
- Protects user during unavailable hours (sleeping, no phone)
- Add Docker build best practices to instructions (background + tail)
- Document phantom system as Critical Component #1
- Add Common Pitfall #30: Phantom notification workflow

Why auto-close:
- User can't always respond to phantom alerts
- Unmonitored position = unlimited risk exposure
- Better to exit with small loss/gain than leave exposed
- Re-entry possible if setup actually good

Files changed:
- app/api/trading/execute/route.ts: Auto-close logic
- .github/copilot-instructions.md: Documentation + build pattern

docker-compose.yml

@@ -11,6 +11,9 @@ services:
       dockerfile: Dockerfile
     container_name: trading-bot-v4
     restart: unless-stopped
+    dns:
+      - 8.8.8.8
+      - 8.8.4.4
     ports:
       - "3001:3000"
     environment:
@@ -80,6 +83,14 @@ services:
   # ================================
   postgres:
     image: postgres:16-alpine
+    command: |
+      postgres
+      -c shared_buffers=128MB
+      -c effective_cache_size=512MB
+      -c work_mem=8MB
+      -c maintenance_work_mem=64MB
+      -c max_connections=20
+      -c random_page_cost=1.1
     container_name: trading-bot-postgres
     restart: unless-stopped
     ports: