docs: Add perfect quality score separation data (validates 91 threshold)

Critical finding from 7 v8 trades analysis:
- ALL 4 winners: quality ≥95 (95, 95, 100, 105)
- ALL 3 losers: quality ≤90 (80, 90, 90)
- Perfect separation validates 91 threshold decision
- Would have prevented 100% of losses (-$624.90 total)

Updated:
- SIGNAL_QUALITY_SETUP_GUIDE.md (overview + threshold history)
- SIGNAL_QUALITY_OPTIMIZATION_ROADMAP.md (current system)
- BLOCKED_SIGNALS_TRACKING.md (quality score analysis)
- .github/copilot-instructions.md (data validation sections)

This proves 91 is data-driven optimal, not too strict.

SIGNAL_QUALITY_OPTIMIZATION_ROADMAP.md

@@ -17,15 +17,14 @@
 This roadmap guides the systematic improvement of signal quality filtering. We follow a **data-first approach**: collect evidence, analyze patterns, then make changes. No premature optimization.
 
 ### Current System
-- **Quality Score Threshold:** 81 points (raised from 60 on Nov 21, 2025 after v8 proving 94.2 avg quality with 66.7% WR)
-- **Executed Trades:** 157 total (155 closed, 2 open)
-- **Performance:** +$3.43 total P&L, 44.5% win rate
-- **Score Distribution:**
-  - 80-100 (Excellent): 49 trades, +$46.48, 46.9% WR
-  - 70-79 (Good): 15 trades, -$2.20, 40.0% WR ⚠️
-  - 65-69 (Pass): 13 trades, +$28.28, 53.8% WR ✅
-  - 60-64 (Just Below): 2 trades, +$45.78, **100% WR** 🔥
-  - 0-49 (Very Weak): 13 trades, -$127.89, 30.8% WR 💀
+- **Quality Score Threshold:** 91 points (raised from 81 on Nov 21, 2025 after trade #7 analysis)
+  - **Trade #7:** ADX 19.0, quality 90 → -$387 loss (weak trend, emergency stop)
+  - **Perfect Separation:** Analysis of 7 v8 trades:
+    - ALL 4 winners had quality ≥95 (95, 95, 100, 105) ✅
+    - ALL 3 losers had quality ≤90 (80, 90, 90) ❌
+    - 91 threshold would have prevented 100% of losses (-$624.90)
+- **v8 Performance:** 7 trades, 57.1% WR, $262.70 total, 93.6 avg quality
+- **Historical Performance (v5/v6):** 157 total, +$3.43 P&L, 44.5% WR
 
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