feat: add notification triggers, comment roles, mention list, and static file serving

- Notify users on ticket assignment and remittance confirm/reject
- Add collector role to comment endpoints
- Add /users/mention-list endpoint for @mention support
- Serve uploaded files via express.static

src/main.ts

@@ -2,12 +2,17 @@ import { NestFactory } from '@nestjs/core';
 import { ValidationPipe } from '@nestjs/common';
 import helmet from 'helmet';
 import { AppModule } from './app.module';
+import { join } from 'path';
+import * as express from 'express';
 
 async function bootstrap() {
   const app = await NestFactory.create(AppModule, {
     logger: ['error', 'warn', 'log'],
   });
 
+  // Serve uploaded files before helmet so they're not blocked
+  app.use('/uploads', express.static(join(__dirname, '..', 'uploads')));
+
   // Security headers
   app.use(
     helmet({