[refs #DIG-8431] Store rater personal details encrypted

[Android63]

Rater email and name are encrypted in the database and an extra email_hash column prevents duplicates.

Also fixed some model relationships and tests.

Note: encrypted columns cannot be searchable or sortable. In Filament Raters table users can now only search by Subject's Academy ID. That should be enough since one subject will be unlikely to have more than a few raters.

[Copilot]

Pull request overview

Stores rater personal details (name/email) encrypted at rest while preserving duplicate prevention via a deterministic email_hash, and updates related model relationships and admin UI/test expectations to match the new storage/search constraints.

Changes:

• Add encrypted casting for Rater.name/Rater.email and maintain a derived email_hash for uniqueness.
• Migrate existing rater rows to encrypted values and introduce (subject_id, email_hash) uniqueness.
• Update Filament tables and model relationship/tests to reflect the new behavior (reduced searchability, relationship key fixes).

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
tests/Unit/Models/RaterTest.php	Updates unit tests to reflect updated/added rater relationships.
tests/Feature/Models/RaterTest.php	Removes outdated relationship expectation test.
database/migrations/2026_06_23_114142_add_email_hash_to_raters_table.php	Adds email_hash, encrypts existing data, and updates unique/index strategy.
CHANGELOG.md	Documents the new encrypted rater storage change.
app/Models/User.php	Fixes User->raters() foreign/local keys to match subject_id usage.
app/Models/Rater.php	Adds encrypted casts, derives email_hash on save, and renames relationship to subject().
app/Filament/Resources/Raters/Tables/RatersTable.php	Removes name/email searching and updates search guidance for encrypted fields.
app/Filament/Resources/Assessments/RelationManagers/RatersRelationManager.php	Switches duplicate detection to email_hash and changes create logic for raters.

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