feat: implement blocked signals tracking system

- Add BlockedSignal table with 25 fields for comprehensive signal analysis
- Track all blocked signals with metrics (ATR, ADX, RSI, volume, price position)
- Store quality scores, block reasons, and detailed breakdowns
- Include future fields for automated price analysis (priceAfter1/5/15/30Min)
- Restore signalQualityVersion field to Trade table

Database changes:
- New table: BlockedSignal with indexes on symbol, createdAt, score, blockReason
- Fixed schema drift from manual changes

API changes:
- Modified check-risk endpoint to save blocked signals automatically
- Fixed hasContextMetrics variable scope (moved to line 209)
- Save blocks for: quality score too low, cooldown period, hourly limit
- Use config.minSignalQualityScore instead of hardcoded 60

Database helpers:
- Added createBlockedSignal() function with try/catch safety
- Added getRecentBlockedSignals(limit) for queries
- Added getBlockedSignalsForAnalysis(olderThanMinutes) for automation

Documentation:
- Created BLOCKED_SIGNALS_TRACKING.md with SQL queries and analysis workflow
- Created SIGNAL_QUALITY_OPTIMIZATION_ROADMAP.md with 5-phase plan
- Documented data-first approach: collect 10-20 signals before optimization

Rationale:
Only 2 historical trades scored 60-64 (insufficient sample size for threshold decision).
Building data collection infrastructure before making premature optimizations.

Phase 1 (current): Collect blocked signals for 1-2 weeks
Phase 2 (next): Analyze patterns and make data-driven threshold decision
Phase 3-5 (future): Automation and ML optimization

prisma/schema.prisma

@@ -77,6 +77,7 @@ model Trade {
   volumeAtEntry     Float?  // Volume relative to MA
   pricePositionAtEntry Float? // Price position in range (0-100%)
   signalQualityScore Int?   // Calculated quality score (0-100)
+  signalQualityVersion String? @default("v1") // Tracks which scoring logic was used
   fundingRateAtEntry Float? // Perp funding rate at entry
   basisAtEntry      Float?  // Perp-spot basis at entry
   
@@ -151,6 +152,52 @@ model SystemEvent {
   @@index([createdAt])
 }
 
+// Blocked signals for analysis (signals that didn't pass quality checks)
+model BlockedSignal {
+  id        String   @id @default(cuid())
+  createdAt DateTime @default(now())
+  
+  // Signal identification
+  symbol           String   // e.g., "SOL-PERP"
+  direction        String   // "long" or "short"
+  timeframe        String?  // "5", "15", "60"
+  
+  // Price at signal time
+  signalPrice      Float    // Price when signal was generated
+  
+  // Market metrics at signal time
+  atr              Float?   // ATR% at signal
+  adx              Float?   // ADX trend strength
+  rsi              Float?   // RSI momentum
+  volumeRatio      Float?   // Volume relative to average
+  pricePosition    Float?   // Position in range (0-100%)
+  
+  // Quality scoring
+  signalQualityScore    Int      // 0-100 score
+  signalQualityVersion  String?  // Which scoring version
+  scoreBreakdown        Json?    // Detailed breakdown of score components
+  minScoreRequired      Int      // What threshold was used (e.g., 65)
+  
+  // Block reason
+  blockReason      String   // "QUALITY_SCORE_TOO_LOW", "DUPLICATE", "COOLDOWN", etc.
+  blockDetails     String?  // Human-readable details
+  
+  // For later analysis: track if it would have been profitable
+  priceAfter1Min   Float?   // Price 1 minute after (filled by monitoring job)
+  priceAfter5Min   Float?   // Price 5 minutes after
+  priceAfter15Min  Float?   // Price 15 minutes after
+  priceAfter30Min  Float?   // Price 30 minutes after
+  wouldHitTP1      Boolean? // Would TP1 have been hit?
+  wouldHitTP2      Boolean? // Would TP2 have been hit?
+  wouldHitSL       Boolean? // Would SL have been hit?
+  analysisComplete Boolean  @default(false) // Has post-analysis been done?
+  
+  @@index([symbol])
+  @@index([createdAt])
+  @@index([signalQualityScore])
+  @@index([blockReason])
+}
+
 // Performance analytics (daily aggregates)
 model DailyStats {
   id        String   @id @default(cuid())