(refactor) removed username from logic

migrations/20251107120039_drop_and_recreate_users_table.sql

@@ -0,0 +1,12 @@
+-- Drop old table
+DROP TABLE IF EXISTS users CASCADE;
+
+-- Create simplified users table
+CREATE TABLE users (
+    id SERIAL PRIMARY KEY,
+    bank_user_id VARCHAR(50) UNIQUE NOT NULL,  -- e.g., "team275-6"
+    password_hash TEXT NOT NULL,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE INDEX IF NOT EXISTS idx_users_bank_user_id ON users(bank_user_id);