feat: Add direction-specific quality thresholds and dynamic collateral display

- Split QUALITY_LEVERAGE_THRESHOLD into separate LONG and SHORT variants
- Added /api/drift/account-health endpoint for real-time collateral data
- Updated settings UI to show separate controls for LONG/SHORT thresholds
- Position size calculations now use dynamic collateral from Drift account
- Updated .env and docker-compose.yml with new environment variables
- LONG threshold: 95, SHORT threshold: 90 (configurable independently)

Files changed:
- app/api/drift/account-health/route.ts (NEW) - Account health API endpoint
- app/settings/page.tsx - Added collateral state, separate threshold inputs
- app/api/settings/route.ts - GET/POST handlers for LONG/SHORT thresholds
- .env - Added QUALITY_LEVERAGE_THRESHOLD_LONG/SHORT variables
- docker-compose.yml - Added new env vars with fallback defaults

Impact:
- Users can now configure quality thresholds independently for LONG vs SHORT signals
- Position size display dynamically updates based on actual Drift account collateral
- More flexible risk management with direction-specific leverage tiers

.env

@@ -395,11 +395,14 @@ MIN_SIGNAL_QUALITY_SCORE=91
 MIN_SIGNAL_QUALITY_SCORE_LONG=90
 MIN_SIGNAL_QUALITY_SCORE_SHORT=80
 # Adaptive Leverage System (Nov 24, 2025)
-# ENABLED Dec 1, 2025: 10x for high-quality signals (Q≥95 LONGs, Q≥90 SHORTs), 5x for borderline
+# ENABLED Dec 1, 2025: 10x for high-quality signals, 5x for borderline
+# Direction-specific thresholds: LONG ≥95, SHORT ≥90
 USE_ADAPTIVE_LEVERAGE=true
 HIGH_QUALITY_LEVERAGE=10
 LOW_QUALITY_LEVERAGE=5
-QUALITY_LEVERAGE_THRESHOLD=95
+QUALITY_LEVERAGE_THRESHOLD_LONG=95
+QUALITY_LEVERAGE_THRESHOLD_SHORT=90
+QUALITY_LEVERAGE_THRESHOLD=95  # Kept for backward compatibility
 SOLANA_ENABLED=true
 SOLANA_POSITION_SIZE=100
 SOLANA_LEVERAGE=5