models/db.rs: User keyed by pubkey_hash/nostr_pubkey/username (pubkey_hash and
seed_fingerprint peppered at rest); Wallet, Session (platform=extension|web|nostr),
UserKey, GrinSlatepack, AuditLog. Dropped all telegram/discord/social-identity
columns and every tip/social/swap struct (swaps land as their own feature unit).
migrations/20260622000001_initial_schema: consolidated clean schema; enum types;
UNIQUE on identity columns; FK ON DELETE (CASCADE/SET NULL) for self-service
erasure; indexes on every lookup column. PostgreSQL 13+.