feat: add title padding parameters and fix recursion error

- Add title_padding, title_x_padding, and title_y_padding to all slide methods
- Add subtitle and content padding parameters for more flexible positioning
- Fix recursion error in add_slide_from_template method
- Add comprehensive test suite for padding functionality
- Create example demonstrating padding features
- Update version to 0.5.0

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Co-Authored-By: Claude <noreply@anthropic.com>
