feat: Complete pyramiding/position stacking implementation (ALL 7 phases)

Phase 1: Configuration
- Added pyramiding config to trading.ts interface and defaults
- Added 6 ENV variables: ENABLE_PYRAMIDING, BASE_LEVERAGE, STACK_LEVERAGE,
  MAX_LEVERAGE_TOTAL, MAX_PYRAMID_LEVELS, STACKING_WINDOW_MINUTES

Phase 2: Database Schema
- Added 5 Trade fields: pyramidLevel, parentTradeId, stackedAt,
  totalLeverageAtEntry, isStackedPosition
- Added index on parentTradeId for pyramid group queries

Phase 3: Execute Endpoint
- Added findExistingPyramidBase() - finds active base trade within window
- Added canAddPyramidLevel() - validates pyramid conditions
- Stores pyramid metadata on new trades

Phase 4: Position Manager Core
- Added pyramidGroups Map for trade ID grouping
- Added addToPyramidGroup() - groups stacked trades by parent
- Added closeAllPyramidLevels() - unified exit for all levels
- Added getTotalPyramidLeverage() - calculates combined leverage
- All exit triggers now close entire pyramid group

Phase 5: Telegram Notifications
- Added sendPyramidStackNotification() - notifies on stack entry
- Added sendPyramidCloseNotification() - notifies on unified exit

Phase 6: Testing (25 tests, ALL PASSING)
- Pyramid Detection: 5 tests
- Pyramid Group Tracking: 4 tests
- Unified Exit: 4 tests
- Leverage Calculation: 4 tests
- Notification Context: 2 tests
- Edge Cases: 6 tests

Phase 7: Documentation
- Updated .github/copilot-instructions.md with full implementation details
- Updated docs/PYRAMIDING_IMPLEMENTATION_PLAN.md status to COMPLETE

Parameters: 4h window, 7x base/stack leverage, 14x max total, 2 max levels
Data-driven: 100% win rate for signals ≤72 bars apart in backtesting

docs/PYRAMIDING_IMPLEMENTATION_PLAN.md

@@ -1,11 +1,41 @@
 # Pyramiding / Signal Stacking Implementation Plan
 
 **Created:** January 9, 2026  
-**Status:** 📋 PLANNED - Ready for Implementation  
+**Completed:** January 9, 2026  
+**Status:** ✅ FULLY IMPLEMENTED AND TESTED  
 **Priority:** HIGH - User-requested feature based on backtested data
 
 ---
 
+## ✅ Implementation Complete!
+
+All 7 phases successfully implemented:
+- ✅ Phase 1: Configuration (config/trading.ts, .env)
+- ✅ Phase 2: Database Schema (prisma/schema.prisma)
+- ✅ Phase 3: Execute Endpoint (app/api/trading/execute/route.ts, lib/database/trades.ts)
+- ✅ Phase 4: Position Manager Core (lib/trading/position-manager.ts)
+- ✅ Phase 5: Telegram Notifications (lib/notifications/telegram.ts)
+- ✅ Phase 6: Testing (25 tests in 6 suites - ALL PASSING)
+- ✅ Phase 7: Documentation (.github/copilot-instructions.md updated)
+
+**Test Coverage:** 25 pyramiding tests across 6 test suites, all passing
+**Total Position Manager Tests:** 164 tests, all passing
+
+**Ready for Production Deployment:**
+```bash
+# 1. Run database migration
+npx prisma migrate dev --name add_pyramiding_fields
+
+# 2. Rebuild Docker container
+docker compose build trading-bot
+docker compose up -d --force-recreate trading-bot
+
+# 3. Verify deployment
+docker logs trading-bot-v4 | grep -i "pyramid"
+```
+
+---
+
 ## 📊 Background & Data-Driven Justification
 
 ### Analysis Results (Jan 9, 2026)