Add CardioAI project with usage instructions

- Add comprehensive README.md with setup and usage instructions
- Add .env.example template (sanitized, no real API keys)
- Add root-level .gitignore to exclude .env and generated files
- Add all project modules (dashboard, predictor)
- Add data file and requirements.txt

CardioAI/.env.example

@@ -0,0 +1,11 @@
+# DeepSeek API 配置
+BASE_URL=https://api.deepseek.com/v1
+DEEPSEEK_API_KEY=your_api_key_here
+MODEL_NAME=deepseek-reasoner
+
+# Flask 配置
+FLASK_ENV=development
+FLASK_DEBUG=True
+
+# 数据文件路径
+DATA_PATH=./data/心血管疾病.xlsx