Enhance rubric generator with better error handling and validation

[thao-1]

Description

This PR enhances the Rubric Generator tool with improved error handling, input validation, and robustness. The changes focus on making the rubric generation process more reliable and maintainable, with better feedback when issues occur.

Key improvements:

• Added comprehensive error handling with retry logic
• Implemented input validation for all parameters
• Enhanced logging for better debugging
• Improved code organisation and type hints
• Added proper resource cleanup

Type of Change

• New feature: A non-breaking change that adds functionality.
• Code style update: Changes that do not affect the meaning of the code.
• Refactoring: A code change that improves code quality.
• Test enhancement: Adding or updating tests.

Proposed Solution

1. Error Handling:

   • Added retry logic with exponential backoff for API calls
   • Implemented proper exception handling with meaningful error messages
   • Added validation for AI-generated rubric structure

2. Input Validation:

   • Added Pydantic models for type checking and validation
   • Implemented custom validators for file URLs and types
   • Added validation for language codes and point scales

3. Code Quality:

   • Improved type hints throughout the codebase
   • Added comprehensive docstrings
   • Organized code into logical methods and classes

4. Testing:

   • Added unit tests for the new validation logic
   • Included test cases for edge cases and error conditions

How to Test

1. Unit Tests:

   cd app/tools/rubric_generator
   python -m pytest tests/ -v