Migrate all test files from resetTestData(t) to testutils.SetupTestDB(t) for isolated per-package test databases.
- Add new feature tests: name history assertions, referral discount preview,
time blockers, email validation, GDPR export, loyalty manual redemption
- Update existing tests to use batch queries and SetupTestDB
- Remove test_helpers.go resetTestData infrastructure
- Add comprehensive user profile tests (442 new lines)
Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>
popertotsandSisyphus