Introduce `display_name` field to `User` struct for human-readable names
in the UI.
This falls back to the user's `slug` if not provided.
Update `AuthenticatedWebUser` and `MyCasesTemplate` to use this new
field for rendering.
Add tests for parsing `display_name` and ensure fallback logic works
correctly.
Update `users.toml.example` to document the new field.
Brummel
2fc7f8ddd2