feat: add batch write optimization to TrajectoryRecorder

[lxcxjxhx]

Motivation

TrajectoryRecorder writes to disk after every LLM interaction, causing excessive I/O operations during long-running tasks. This PR adds a buffer mechanism to batch writes and reduce disk I/O.

Changes

1. TrajectoryRecorder Buffer (trae_agent/utils/trajectory_recorder.py)

• Added \�uffer_size\ parameter to _init_\ (default: 10)
• Added _pending_writes\ counter to track buffered writes
• Added \lush()\ method for manual buffer flushing
• Implemented batch write logic in
  ecord_llm_interaction()\
• Automatically saves to disk when buffer is full

2. Buffer Management

• Each interaction increments _pending_writes\ counter
• When counter reaches \�uffer_size, automatically calls \save_trajectory()\
• Manual \lush()\ method ensures data can be saved immediately when needed
• Default buffer size of 10 is configurable

Testing

• Created \ ests/utils/test_trajectory_recorder.py\ with 7 test cases
• Covers buffer mechanism, batch writes, manual flush, and edge cases
• All tests pass

Checklist

• Code follows project coding standards
• Added comprehensive test cases
• All tests pass
• No unnecessary dependencies added
• Changes are backward compatible