Admin site related records

[itsharrykim]

This pull request introduces enhancements to the admin interface's handling and display of relation (edge) fields for Ent models. It adds richer metadata for relations, improves UI/UX for navigating related records, and refines field configuration and discovery. The most important changes are summarized below.

Relation Field Metadata and Discovery

• Extended FieldConfig to include relation metadata: Relation, RelationTarget, and RelationMany, allowing the admin UI to better understand and display entity relationships.
• Improved relation field extraction in extractRelationFields by determining the target type and cardinality (one/many) using the new relationTargetFromEdgeType helper. [1] [2]
• Added tests to ensure that relation metadata is correctly discovered and preserved for both directions of entity relationships. [1] [2]

Field Configuration Improvements

• Added a Column field to FieldConfig and logic to compute the database column name from struct tags or field names, ensuring more accurate field mapping. [1] [2] [3]

Admin UI/UX Enhancements

• Updated the grid and record drawer views to render relation fields as links to related records, improving navigation between related entities. [1] [2]
• Added a "related filter chip" UI component and logic to indicate and clear when a grid is filtered by a related record, and hid the "Add record" button in such cases to prevent context confusion. [1] [2] [3] [4] [5] [6] [7] [8]

Styling Updates

• Added and refined CSS classes for relation links and filter chips to provide a consistent and accessible visual style for relation navigation elements. [1] [2] [3] [4]

Miscellaneous

• Added an optional QueryModifier hook to ModelConfig for customizing Ent queries, supporting more advanced data loading scenarios. [1] [2]

These changes collectively improve the admin experience for working with related data, making relationships clearer and navigation more intuitive.