SQL Date extends from util.Date but do not support toInstant

[jenspapenhagen]

Linked Issue

Closes #79

Description

the SQL Date extends from java.util.Date but do not support toInstant()

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Refactoring (no functional changes)
• Performance improvement
• Test coverage improvement

Changes Made

SPEC Compliance

• This PR implements/fixes spec compliance
• Spec section(s) affected:
• Spec version:

Testing

• All existing tests pass
• Added new tests for changes
• Tests cover edge cases and spec compliance

Pre-submission Checklist

• My code follows the project's coding standards
• I have run code formatting/linting tools
• I have added tests that prove my fix/feature works
• New and existing tests pass locally
• I have updated documentation if needed
• I have reviewed the TOON specification for relevant sections

Breaking Changes

• No breaking changes
• Breaking changes (describe migration path below)

Additional Context

[github-actions]

Code Coverage

Overall Project	98.22%	🍏
Files changed	100%	🍏

File	Coverage
JsonNormalizer.java	99.39%	🍏