- Consolidate migrations: merge 002/003 into 001_initial with UNIQUE did constraint
- Add foreign key: active_identity.activeDid REFERENCES accounts.did ON DELETE RESTRICT
- Replace empty string defaults with NULL for proper empty state handling
- Implement atomic smart deletion with auto-switch logic in IdentitySwitcherView
- Add DAL methods: $getAllAccountDids, $getActiveDid, $setActiveDid, $pickNextAccountDid
- Add migration bootstrapping to auto-select first account if none selected
- Block deletion of last remaining account with user notification
Refs: doc/active-pointer-smart-deletion-pattern.md
