feat: Add database init on startup and documentation

- Add lifespan handler to main.py for automatic DB table creation
- Expand .env.example with detailed variable documentation
- Add AUDIT_REPORT.md with comprehensive product/technical review
- Add STRATEGY_SCHEMA.md as single source of truth for strategy config
- Remove redundant init_db.py script (DB init now handled by app startup)

src/backend/.env.example

@@ -1,11 +1,68 @@
+# Randebu Trading Bot - Environment Variables Template
+# Copy this file to .env and fill in your values
+
+# =============================================================================
+# DATABASE
+# =============================================================================
+
+# SQLite database path (relative or absolute)
+# Example: sqlite:///./data/app.db
 DATABASE_URL=sqlite:///./data/app.db
+
+# =============================================================================
+# AUTHENTICATION
+# =============================================================================
+
+# Secret key for JWT token signing
+# Generate with: python -c "import secrets; print(secrets.token_hex(32))"
 SECRET_KEY=your-super-secret-key-change-in-production
+
+# JWT algorithm (HS256 is recommended)
 JWT_ALGORITHM=HS256
+
+# Token expiration time in minutes (1440 = 24 hours)
 ACCESS_TOKEN_EXPIRE_MINUTES=1440
+
+# =============================================================================
+# MINIMAX LLM
+# =============================================================================
+
+# MiniMax API key (get from https://platform.minimax.chat/)
 MINIMAX_API_KEY=your-minimax-api-key
+
+# MiniMax model to use
+# Common options: MiniMax-Text-01, MiniMax-M2.1
 MINIMAX_MODEL=MiniMax-Text-01
-AVE_API_KEY=your-ave-cloud-api-key
+
+# =============================================================================
+# AVE CLOUD API
+# =============================================================================
+
+# AVE Cloud API key (get from https://cloud.ave.ai/)
+AVE_API_KEY=your-ave-api-key
+
+# AVE Cloud plan tier
+# Options: free, normal, pro
+# Note: Free tier has 1 TPS limit, Pro required for WebSocket
 AVE_API_PLAN=free
+
+# =============================================================================
+# SERVER CONFIGURATION
+# =============================================================================
+
+# Server host (0.0.0.0 for all interfaces)
 HOST=0.0.0.0
+
+# Server port
 PORT=8000
+
+# Debug mode (set to false in production)
 DEBUG=false
+
+# =============================================================================
+# FRONTEND CONFIGURATION (for reference)
+# =============================================================================
+
+# Frontend environment variables (set in frontend .env file):
+# VITE_API_URL=https://bot.yourdomain.com/api
+# VITE_WS_URL=wss://bot.yourdomain.com/ws