fix: Fix trading precision issues and improve error handling

- Fix quantity precision calculation for Binance, OKX, Bybit, Bitget, Deepcoin exchanges
- Improve OpenRouter API error handling with detailed error messages
- Add SECRET_KEY validation in Docker deployment entrypoint
- Fix K-line chart measurement tool click issue
- Adapt billing page text colors for dark theme
- Update frontend build files

scripts/generate-secret-key.sh

@@ -0,0 +1,33 @@
+#!/bin/bash
+# Helper script to generate a secure SECRET_KEY for QuantDinger
+# Usage: ./scripts/generate-secret-key.sh
+
+set -e
+
+ENV_FILE="backend_api_python/.env"
+
+# Check if .env exists
+if [ ! -f "$ENV_FILE" ]; then
+    echo "Error: $ENV_FILE not found"
+    echo "Please run: cp backend_api_python/env.example backend_api_python/.env"
+    exit 1
+fi
+
+# Generate a secure random key
+NEW_KEY=$(python3 -c "import secrets; print(secrets.token_hex(32))")
+
+# Update SECRET_KEY in .env file
+if [[ "$OSTYPE" == "darwin"* ]]; then
+    # macOS
+    sed -i '' "s|^SECRET_KEY=.*|SECRET_KEY=$NEW_KEY|" "$ENV_FILE"
+else
+    # Linux
+    sed -i "s|^SECRET_KEY=.*|SECRET_KEY=$NEW_KEY|" "$ENV_FILE"
+fi
+
+echo "✅ SECRET_KEY generated and updated in $ENV_FILE"
+echo ""
+echo "Generated key: $NEW_KEY"
+echo ""
+echo "You can now start the application:"
+echo "  docker-compose up -d --build"