- Add automatic re-hashing of legacy SHA-256 PINs to Argon2id on
successful verification, returning new hash to frontend for persistence
- Use constant-time comparison (subtle::ConstantTimeEq) for both
Argon2id and legacy SHA-256 hash verification
- Add unit tests for hash_pin, verify_pin (Argon2id and legacy paths),
re-hashing flow, error cases, and hex encoding roundtrip
- Update frontend to handle VerifyPinResult struct and save rehashed
PIN hash via profile update
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Each profile gets its own SQLite database file for complete data isolation.
Profile selection screen at launch, sidebar switcher for quick switching,
and optional 4-6 digit PIN for privacy. Existing database becomes the
default profile with seamless upgrade.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
