feat: enhance LocalAgent configuration and UI components

- Updated .env.example to provide clearer configuration instructions and API key setup.
- Removed debug_env.py as it was no longer needed.
- Refactored main.py to streamline application initialization and workspace setup.
- Introduced a new HistoryManager for managing task execution history.
- Enhanced UI components in chat_view.py and task_guide_view.py to improve user interaction and code preview functionality.
- Added loading indicators and improved task history display in the UI.
- Implemented unit tests for history management and intent classification.

requirements.txt

@@ -14,3 +14,6 @@ openpyxl>=3.1.0         # Excel 处理
 python-docx>=1.0.0      # Word 文档处理
 PyPDF2>=3.0.0           # PDF 处理
 chardet>=5.0.0          # 文件编码检测
+
+# 测试依赖（可选）
+pytest>=7.0.0           # 单元测试框架