Add signal quality version tracking to database

- Added signalQualityVersion field to Trade model
- Tracks which scoring logic version was used for each trade
- v1: Original logic (price position < 5% threshold)
- v2: Added volume compensation for low ADX
- v3: CURRENT - Stricter logic requiring ADX > 18 for extreme positions (< 15%)

This enables future analysis to:
- Compare performance between logic versions
- Filter trades by scoring algorithm
- Data-driven improvements based on clean datasets

All new trades will be marked as v3. Old trades remain null/v1 for comparison.

prisma/schema.prisma

@@ -102,6 +102,12 @@ model Trade {
   signalStrength   String?  // "strong", "moderate", "weak"
   timeframe        String?  // "5", "15", "60"
   
+  // Signal quality logic version tracking
+  signalQualityVersion String? @default("v1") // Track which scoring logic was used
+  // v1: Original logic with price position < 5% threshold
+  // v2: Added volume compensation for low ADX (2025-11-07)
+  // v3: Stricter - price position < 15% requires ADX > 18 (2025-11-07)
+  
   // Status
   status           String   @default("open") // "open", "closed", "failed", "phantom"
   isTestTrade      Boolean  @default(false) // Flag test trades for exclusion from analytics