Add complete Ouroboros trading system with TDD test suite

Implement the full autonomous trading agent architecture:
- KIS broker with async API, token refresh, leaky bucket rate limiter, and hash key signing
- Gemini-powered decision engine with JSON parsing and confidence threshold enforcement
- Risk manager with circuit breaker (-3% P&L) and fat finger protection (30% cap)
- Evolution engine for self-improving strategy generation via failure analysis
- 35 passing tests written TDD-first covering risk, broker, and brain modules
- CI/CD pipeline, Docker multi-stage build, and AI agent context docs

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.env.example

@@ -0,0 +1,23 @@
+# Korea Investment Securities API
+KIS_APP_KEY=your_app_key_here
+KIS_APP_SECRET=your_app_secret_here
+KIS_ACCOUNT_NO=12345678-01
+KIS_BASE_URL=https://openapivts.koreainvestment.com:9443
+
+# Google Gemini
+GEMINI_API_KEY=your_gemini_api_key_here
+GEMINI_MODEL=gemini-pro
+
+# Risk Management
+CIRCUIT_BREAKER_PCT=-3.0
+FAT_FINGER_PCT=30.0
+CONFIDENCE_THRESHOLD=80
+
+# Database
+DB_PATH=data/trade_logs.db
+
+# Rate Limiting
+RATE_LIMIT_RPS=10.0
+
+# Trading Mode (paper / live)
+MODE=paper