Annotate setup and draw methods with return types

[zendrx]

Added type annotations to the setup and draw methods to specify their return types as Nil, enhancing code clarity and type safety.

Description

Please provide a summary of the changes and which issue is fixed.

Fixes #(issue)

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Performance improvement
• Code refactoring
• Build/CI pipeline change

Checklist

• My code follows the code style of this project
• I have ran crystal tool format on my changes
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have updated the documentation accordingly
• I have added an entry to CHANGELOG.md

Platform Impact

• Android
• iOS
• Both

Testing Done

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Screenshots (if appropriate)

Additional Context

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