Improve soft-deletion

[aalmada]

Pull Request Template

Description

Refactor soft-deletion code. Add indexes.

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
• Code refactoring
• Performance improvement
• Test addition/update

Related Issues

Fixes #

Changes Made

Testing

• Unit tests pass (dotnet test)
• Build succeeds (dotnet build)
• Code formatting is correct (dotnet format --verify-no-changes)
• No new analyzer warnings
• Manual testing completed

Checklist

• My code follows the project's coding standards
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• 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
• Any dependent changes have been merged and published

Screenshots (if applicable)

Additional Notes

[github-actions]

Package	Line Rate	Branch Rate	Health
BookStore.Shared	14%	5%	❌
BookStore.ApiService	11%	15%	❌
Summary	11% (830 / 7466)	14% (328 / 2292)	❌