fix: user invite email not sending and null variables

- Add missing BullModule queue registration and BullBoardModule to UsersModule
- Add invitingUser to event payloads to track who sent the invite
- Fix incorrect global variable in SendInviteUsersMailMessage (__views_dir -> __images_dirname)
- Use invitingUser as fromUser instead of invited user in email
- Update processors to use BullMQ pattern

Fixes issues:
1. Email not sending due to missing queue/processor registration
2. Null variables in email (firstName/lastName) because fromUser was the invited user
3. Image attachment failing due to wrong path

packages/server/src/modules/SaleReceipts/commands/SaleReceiptMailNotification.ts

@@ -1,4 +1,4 @@
-import { InjectQueue } from '@nestjs/bull';
+import { InjectQueue } from '@nestjs/bullmq';
 import { Queue } from 'bullmq';
 import {
   DEFAULT_RECEIPT_MAIL_CONTENT,