Sets up the next session to migrate models.py DateTime columns to
timezone=True and remove the defensive .replace(tzinfo=None) shell.
Surfaces evidence and open questions (SQLAlchemy/SQLite round-trip
behaviour, existing data migration, pw_changed_at marker semantics)
rather than pre-baking an implementation plan that could bury false
premises.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
