fix: bypass ValidationPipe for multipart comments, auto-create uploads dir, expand client roles

- Use @Body() body: any in comment controller to skip global ValidationPipe
  which was rejecting multipart form bodies with forbidNonWhitelisted
- Auto-create uploads/ directory on startup to prevent ENOENT on file uploads
- Restrict file uploads to images only (remove pdf)
- Allow technician/collector roles to update clients (was manager-only)

src/comment/comment.controller.ts

@@ -12,7 +12,6 @@ import {
 import { AuthGuard } from '@nestjs/passport';
 import { FileFieldsInterceptor } from '@nestjs/platform-express';
 import { CommentService } from './comment.service';
-import { CreateCommentDto } from './dto/create-comment.dto';
 import { Roles } from '../common/decorators/roles.decorator';
 import { RolesGuard } from '../common/guards/roles.guard';
 import { TenantGuard } from '../common/guards/tenant.guard';
@@ -39,10 +38,12 @@ export class CommentController {
   async create(
     @CurrentUser() user: CurrentUserPayload,
     @Param('ticketId') ticketId: string,
-    @Body() body: CreateCommentDto,
+    @Body() body: any,
     @UploadedFiles() files?: { files?: Express.Multer.File[] },
   ) {
-    const content = body.content;
+    let content = body?.content;
+    if (Array.isArray(content)) content = content[0];
+    if (typeof content !== 'string') content = String(content ?? '');
     if (!content || content.length > 50000) {
       throw new BadRequestException('Content must be between 1 and 50000 characters');
     }