Add auto-generated account numbers and member numbers

6-digit random numbers generated on create, unique per company. Member
number column added to member table. Both displayed in UI tables.

packages/backend/src/db/schema/accounts.ts

@@ -49,6 +49,7 @@ export const members = pgTable('member', {
   companyId: uuid('company_id')
     .notNull()
     .references(() => companies.id),
+  memberNumber: varchar('member_number', { length: 50 }),
   firstName: varchar('first_name', { length: 100 }).notNull(),
   lastName: varchar('last_name', { length: 100 }).notNull(),
   dateOfBirth: date('date_of_birth'),