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

lib/drift/client.ts

@@ -102,8 +102,12 @@ export class DriftService {
           error?.code === 'EAI_AGAIN' ||
           error?.cause?.code === 'EAI_AGAIN'
         
+        console.log(`🔍 Error detection: isTransient=${isTransient}, attempt=${attempt}/${maxRetries}`)
+        console.log(`🔍 Error details: message="${error?.message}", code="${error?.code}", cause.code="${error?.cause?.code}"`)
+        
         if (!isTransient || attempt === maxRetries) {
           // Non-transient error or max retries reached - fail immediately
+          console.log(`❌ Not retrying: isTransient=${isTransient}, maxed=${attempt === maxRetries}`)
           throw error
         }