fix: Response wrapping, error logging, and controller hardening (COA 3)

- HttpExceptionFilter: Log actual error details for non-HttpExceptions (was silently swallowing 500s)
- ServersService: Return null fields instead of 404 for new licenses without servers
- NotificationsController: Wrap config responses as { config } to match frontend expectations
- WebstoreController: Wrap config responses as { config } to match frontend expectations
- ChatController: Replace ParseIntPipe with manual parseInt (400 on missing optional param)
- WipesController: Same ParseIntPipe fix for history limit param

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend-nest/src/modules/wipes/wipes.controller.ts

@@ -7,7 +7,6 @@ import {
   Body,
   Param,
   Query,
-  ParseIntPipe,
   UseGuards,
 } from '@nestjs/common';
 import { ApiTags, ApiBearerAuth, ApiOperation, ApiQuery } from '@nestjs/swagger';
@@ -81,9 +80,10 @@ export class WipesController {
   @ApiQuery({ name: 'limit', required: false, example: 50 })
   getHistory(
     @CurrentTenant() licenseId: string,
-    @Query('limit', new ParseIntPipe({ optional: true })) limit?: number,
+    @Query('limit') limit?: string,
   ) {
-    return this.wipesService.getHistory(licenseId, limit || 50);
+    const limitNum = limit ? parseInt(limit, 10) : 50;
+    return this.wipesService.getHistory(licenseId, limitNum);
   }
 
   @Post('trigger')