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/services/simulation_runner.py

@@ -280,7 +280,8 @@ class SimulationRunner:
     def start_simulation(
         cls,
         simulation_id: str,
-        platform: str = "parallel"  # twitter / reddit / parallel
+        platform: str = "parallel",  # twitter / reddit / parallel
+        max_rounds: int = None  # 最大模拟轮数（可选，用于截断过长的模拟）
     ) -> SimulationRunState:
         """
         启动模拟
@@ -288,6 +289,7 @@ class SimulationRunner:
         Args:
             simulation_id: 模拟ID
             platform: 运行平台 (twitter/reddit/parallel)
+            max_rounds: 最大模拟轮数（可选，用于截断过长的模拟）
             
         Returns:
             SimulationRunState
@@ -313,6 +315,13 @@ class SimulationRunner:
         minutes_per_round = time_config.get("minutes_per_round", 30)
         total_rounds = int(total_hours * 60 / minutes_per_round)
         
+        # 如果指定了最大轮数，则截断
+        if max_rounds is not None and max_rounds > 0:
+            original_rounds = total_rounds
+            total_rounds = min(total_rounds, max_rounds)
+            if total_rounds < original_rounds:
+                logger.info(f"轮数已截断: {original_rounds} -> {total_rounds} (max_rounds={max_rounds})")
+        
         state = SimulationRunState(
             simulation_id=simulation_id,
             runner_status=RunnerStatus.STARTING,
@@ -358,6 +367,10 @@ class SimulationRunner:
                 "--config", config_path,  # 使用完整配置文件路径
             ]
             
+            # 如果指定了最大轮数，添加到命令行参数
+            if max_rounds is not None and max_rounds > 0:
+                cmd.extend(["--max-rounds", str(max_rounds)])
+            
             # 创建主日志文件，避免 stdout/stderr 管道缓冲区满导致进程阻塞
             main_log_path = os.path.join(sim_dir, "simulation.log")
             main_log_file = open(main_log_path, 'w', encoding='utf-8')