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.

llm/prompts.py

@@ -108,7 +108,8 @@ import shutil
 from pathlib import Path
 
 # 工作目录（固定，不要修改）
-WORKSPACE = Path(__file__).parent
+# 代码保存在 workspace/codes/ 目录，向上一级是 workspace
+WORKSPACE = Path(__file__).parent.parent
 INPUT_DIR = WORKSPACE / "input"
 OUTPUT_DIR = WORKSPACE / "output"