- Introduced application-wide constants for file uploads, image processing, pagination, and authentication in `constants.py`.
- Implemented synchronous and asynchronous board ownership verification functions in `ownership.py`.
- Created a base repository class with common CRUD operations in `repository.py`.
- Added standard response utilities for error and success messages in `responses.py`.
- Refactored image validation to utilize constants for file size and MIME types.
- Enhanced frontend components with consistent styling and validation utilities for forms.
- Established global styles for buttons, forms, loading indicators, and messages to ensure a cohesive UI experience.
