critical: MANDATORY quality score check in execute endpoint

ROOT CAUSE:
- Execute endpoint calculated quality score but NEVER checked it
- After timeframe='5' validation, proceeded directly to execution
- TradingView sent signal with all metrics=0 (ADX, ATR, RSI, etc.)
- Quality scored as 30, but no threshold check existed
- Position opened with 909.77 size at quality 30 (need 90+ for LONG)

THE FIX:
- Added MANDATORY quality check after timeframe validation
- Blocks execution if score < minQualityScore (90 LONG, 95 SHORT)
- Returns HTTP 400 with detailed error message
- Logs Quality check passed OR ❌ QUALITY TOO LOW:

AFFECTED TRADES:
- cmihwkjmb0088m407lqd8mmbb: Quality 30 LONG (stopped out)
- cmih6ghn20002ql07zxfvna1l: Quality 50 LONG (stopped out)
- cmih5vrpu0001ql076mj3nm63: Quality 50 LONG (stopped out)

This is a FINANCIAL SAFETY critical fix - prevents low-quality trades.

app/api/trading/execute/route.ts

@@ -189,6 +189,25 @@ export async function POST(request: NextRequest): Promise<NextResponse<ExecuteTr
     }
     
     console.log(`✅ 5min signal confirmed - proceeding with trade execution`)
+    
+    // CRITICAL FIX (Nov 27, 2025): Verify quality score meets minimum threshold
+    // Bug: Quality 30 trade executed because no quality check after timeframe validation
+    if (qualityResult.score < minQualityScore) {
+      console.log(`❌ QUALITY TOO LOW: ${qualityResult.score} < ${minQualityScore} threshold for ${body.direction.toUpperCase()}`)
+      console.log(`   Reasons: ${qualityResult.reasons.join(', ')}`)
+      return NextResponse.json({
+        success: false,
+        error: 'Quality score too low',
+        message: `Signal quality ${qualityResult.score} below ${minQualityScore} minimum for ${body.direction.toUpperCase()} (reasons: ${qualityResult.reasons.join(', ')})`,
+        quality: {
+          score: qualityResult.score,
+          threshold: minQualityScore,
+          reasons: qualityResult.reasons
+        }
+      }, { status: 400 })
+    }
+    
+    console.log(`✅ Quality check passed: ${qualityResult.score} >= ${minQualityScore}`)
 
     // Initialize Drift service and check account health before sizing
     const driftService = await initializeDriftService()