Add entity_type column to evaluation_rule_entities

[dmjb]

This simplifies some queries which I am working on in another PR.

A subsequent PR will backfill the column for existing data, and make the column non-nullable.

Summary

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Fixes #(related issue)

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• Bug fix (resolves an issue without affecting existing features)
• Feature (adds new functionality without breaking changes)
• Breaking change (may impact existing functionalities or require documentation updates)
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• Refactoring or test improvements (no bug fixes or new functionality)

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Review Checklist:

• Reviewed my own code for quality and clarity.
• Added comments to complex or tricky code sections.
• Updated any affected documentation.
• Included tests that validate the fix or feature.
• Checked that related changes are merged.

[coveralls]

coverage: 54.351% (+0.01%) from 54.338%
when pulling dea54db on entity-type-column-entity-rules-history
into bbbb682 on main.