Add accounts, members, and processor-agnostic payment linking

- account table (billing entity, soft-delete, company-scoped)
- member table (people on an account, is_minor from DOB)
- account_processor_link table (maps accounts to any payment
  processor — stripe, global_payments — instead of stripe_customer_id
  directly on account)
- Full CRUD routes + search (name, email, phone, account_number)
- Member routes nested under accounts with isMinor auto-calculation
- Zod validation schemas in @forte/shared
- 19 tests passing

packages/backend/src/plugins/database.ts

@@ -3,8 +3,9 @@ import { drizzle } from 'drizzle-orm/postgres-js'
 import postgres from 'postgres'
 import * as storeSchema from '../db/schema/stores.js'
 import * as userSchema from '../db/schema/users.js'
+import * as accountSchema from '../db/schema/accounts.js'
 
-const schema = { ...storeSchema, ...userSchema }
+const schema = { ...storeSchema, ...userSchema, ...accountSchema }
 
 declare module 'fastify' {
   interface FastifyInstance {