Enhance simulation configuration and management features

- Added support for a `max_rounds` parameter in simulation API, allowing users to limit the number of simulation rounds, improving control over simulation duration.
- Updated README.md to reflect the new `max_rounds` parameter and its usage in simulation requests.
- Enhanced error handling for `max_rounds` input validation to ensure it is a positive integer.
- Modified simulation runner and related scripts to incorporate `max_rounds` functionality, ensuring consistent application across Twitter and Reddit simulations.
- Improved logging to indicate when the number of rounds is truncated due to the `max_rounds` setting, enhancing traceability during simulation execution.

backend/app/config.py

@@ -24,6 +24,9 @@ class Config:
     SECRET_KEY = os.environ.get('SECRET_KEY', 'mirofish-secret-key')
     DEBUG = os.environ.get('FLASK_DEBUG', 'True').lower() == 'true'
     
+    # JSON配置 - 禁用ASCII转义，让中文直接显示（而不是 \uXXXX 格式）
+    JSON_AS_ASCII = False
+    
     # LLM配置（统一使用OpenAI格式）
     LLM_API_KEY = os.environ.get('LLM_API_KEY')
     LLM_BASE_URL = os.environ.get('LLM_BASE_URL', 'https://api.openai.com/v1')