Add email+password auth alongside Google: argon2id hashing; users gains
password_hash/email_verified/is_active and google_sub becomes nullable (migration
0022); a single-use, hashed auth_tokens table for email verification + password
reset. Registration creates a pending (inactive, unverified) account + an access
request; sign-in needs verified email AND admin approval. Anti-enumeration: uniform
register/login/reset responses (a correct-password owner still gets a specific
pending reason). allow_registration flag (DB-tunable). Admin users-list + role
endpoint (guards: not self, not demo, not the last admin); approving access (or a
manual whitelist add) now activates the matching pending account. current_user
rejects deactivated accounts. Verified end-to-end via curl + DB.
