Delete 23 unused files:
- AdminMiddleware (never registered, SuperAdminMiddleware used instead)
- 4 form requests with no controller references
- AbilityResource/Collection and ExchangeRateLogResource/Collection (zero usage)
- Customer/RecurringInvoiceResource and Collection (no controller or nested reference)
- 10 Customer Collection classes whose Resources are only used via new, never ::collection()
de06c335ac