fix(critical): Unify quality score calculation across check-risk and execute

PROBLEM:
- check-risk calculated quality score: 60, 70 (PASSED)
- execute calculated quality score: 35, 45 (should have BLOCKED)
- Two different functions with different logic caused trades to bypass validation

ROOT CAUSE:
Two separate scoring functions existed:
1. scoreSignalQuality() in check-risk (detailed, 95% price threshold)
2. calculateQualityScore() in execute (simpler, 90% price threshold)

Example with pricePosition=96.4%, volumeRatio=0.9:
- check-risk: Checks >95, volumeRatio>1.4 failed → -15 + bonuses = 60 ✅ PASSED
- execute: Checks >90 → -15 + bonuses = 35 ❌ Should block but already opened

SOLUTION:
1. Created lib/trading/signal-quality.ts with unified scoreSignalQuality()
2. Both endpoints now import and use SAME function
3. Consistent scoring logic: 95% price threshold, volume breakout bonus
4. Returns detailed reasons for debugging

IMPACT:
- Quality scores now MATCH between check-risk and execute
- No more trades bypassing validation due to calculation differences
- Better debugging with quality reasons logged

Files changed:
- NEW: lib/trading/signal-quality.ts (unified scoring function)
- MODIFIED: app/api/trading/check-risk/route.ts (import shared function)
- MODIFIED: app/api/trading/execute/route.ts (import shared function)
- REMOVED: Duplicate calculateQualityScore() from execute
- REMOVED: Duplicate scoreSignalQuality() from check-risk

lib/trading/signal-quality.ts

@@ -0,0 +1,147 @@
+/**
+ * Signal Quality Scoring
+ * 
+ * Unified quality scoring logic used by both check-risk and execute endpoints.
+ * Ensures consistent scoring across the trading pipeline.
+ */
+
+export interface SignalQualityResult {
+  score: number
+  passed: boolean
+  reasons: string[]
+}
+
+/**
+ * Calculate signal quality score based on technical indicators
+ * 
+ * Scoring breakdown:
+ * - Base: 50 points
+ * - ATR (volatility): -20 to +10 points
+ * - ADX (trend strength): -15 to +15 points
+ * - RSI (momentum): -10 to +10 points
+ * - Volume: -10 to +15 points
+ * - Price position: -15 to +5 points
+ * - Volume breakout bonus: +10 points
+ * 
+ * Total range: ~15-115 points (realistically 30-100)
+ * Threshold: 60 points minimum for execution
+ */
+export function scoreSignalQuality(params: {
+  atr: number
+  adx: number
+  rsi: number
+  volumeRatio: number
+  pricePosition: number
+  direction: 'long' | 'short'
+  minScore?: number // Configurable minimum score threshold
+}): SignalQualityResult {
+  let score = 50 // Base score
+  const reasons: string[] = []
+
+  // ATR check (volatility gate: 0.15% - 2.5%)
+  if (params.atr > 0) {
+    if (params.atr < 0.15) {
+      score -= 15
+      reasons.push(`ATR too low (${params.atr.toFixed(2)}% - dead market)`)
+    } else if (params.atr > 2.5) {
+      score -= 20
+      reasons.push(`ATR too high (${params.atr.toFixed(2)}% - too volatile)`)
+    } else if (params.atr >= 0.15 && params.atr < 0.4) {
+      score += 5
+      reasons.push(`ATR moderate (${params.atr.toFixed(2)}%)`)
+    } else {
+      score += 10
+      reasons.push(`ATR healthy (${params.atr.toFixed(2)}%)`)
+    }
+  }
+
+  // ADX check (trend strength: want >18)
+  if (params.adx > 0) {
+    if (params.adx > 25) {
+      score += 15
+      reasons.push(`Strong trend (ADX ${params.adx.toFixed(1)})`)
+    } else if (params.adx < 18) {
+      score -= 15
+      reasons.push(`Weak trend (ADX ${params.adx.toFixed(1)})`)
+    } else {
+      score += 5
+      reasons.push(`Moderate trend (ADX ${params.adx.toFixed(1)})`)
+    }
+  }
+
+  // RSI check (momentum confirmation)
+  if (params.rsi > 0) {
+    if (params.direction === 'long') {
+      if (params.rsi > 50 && params.rsi < 70) {
+        score += 10
+        reasons.push(`RSI supports long (${params.rsi.toFixed(1)})`)
+      } else if (params.rsi > 70) {
+        score -= 10
+        reasons.push(`RSI overbought (${params.rsi.toFixed(1)})`)
+      }
+    } else { // short
+      if (params.rsi < 50 && params.rsi > 30) {
+        score += 10
+        reasons.push(`RSI supports short (${params.rsi.toFixed(1)})`)
+      } else if (params.rsi < 30) {
+        score -= 10
+        reasons.push(`RSI oversold (${params.rsi.toFixed(1)})`)
+      }
+    }
+  }
+
+  // Volume check (want > 1.0 = above average)
+  if (params.volumeRatio > 0) {
+    if (params.volumeRatio > 1.5) {
+      score += 15
+      reasons.push(`Very strong volume (${params.volumeRatio.toFixed(2)}x avg)`)
+    } else if (params.volumeRatio > 1.2) {
+      score += 10
+      reasons.push(`Strong volume (${params.volumeRatio.toFixed(2)}x avg)`)
+    } else if (params.volumeRatio < 0.8) {
+      score -= 10
+      reasons.push(`Weak volume (${params.volumeRatio.toFixed(2)}x avg)`)
+    }
+  }
+
+  // Price position check (avoid chasing vs breakout detection)
+  if (params.pricePosition > 0) {
+    if (params.direction === 'long' && params.pricePosition > 95) {
+      // High volume breakout at range top can be good
+      if (params.volumeRatio > 1.4) {
+        score += 5
+        reasons.push(`Volume breakout at range top (${params.pricePosition.toFixed(0)}%, vol ${params.volumeRatio.toFixed(2)}x)`)
+      } else {
+        score -= 15
+        reasons.push(`Price near top of range (${params.pricePosition.toFixed(0)}%) - risky long`)
+      }
+    } else if (params.direction === 'short' && params.pricePosition < 5) {
+      // High volume breakdown at range bottom can be good
+      if (params.volumeRatio > 1.4) {
+        score += 5
+        reasons.push(`Volume breakdown at range bottom (${params.pricePosition.toFixed(0)}%, vol ${params.volumeRatio.toFixed(2)}x)`)
+      } else {
+        score -= 15
+        reasons.push(`Price near bottom of range (${params.pricePosition.toFixed(0)}%) - risky short`)
+      }
+    } else {
+      score += 5
+      reasons.push(`Price position OK (${params.pricePosition.toFixed(0)}%)`)
+    }
+  }
+
+  // Volume breakout bonus (high volume can override other weaknesses)
+  if (params.volumeRatio > 1.8 && params.atr < 0.6) {
+    score += 10
+    reasons.push(`Volume breakout compensates for low ATR`)
+  }
+
+  const minScore = params.minScore || 60
+  const passed = score >= minScore
+
+  return {
+    score,
+    passed,
+    reasons,
+  }
+}