chore: apply ESLint auto-fix across entire backend

Reformats code style (line breaks, indentation, type annotations)
without changing logic. Also includes minor feature additions bundled
in the same lint run (stats service, user-settings groups, agrarmonitor
polling improvements).

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

paperless-backend/src/auth/api-key.guard.ts

@@ -1,4 +1,10 @@
-import { CanActivate, ExecutionContext, Injectable, Logger, UnauthorizedException } from '@nestjs/common';
+import {
+  CanActivate,
+  ExecutionContext,
+  Injectable,
+  Logger,
+  UnauthorizedException,
+} from '@nestjs/common';
 import { ApiKeysService } from './api-keys.service';
 
 @Injectable()
@@ -33,8 +39,8 @@ export class ApiKeyGuard implements CanActivate {
 
     this.logger.log(
       `[${method} ${url}] key source: ${apiKey ? source : 'NONE'} | ` +
-      `headers: ${JSON.stringify(Object.keys(request.headers))} | ` +
-      `key prefix: ${apiKey ? String(apiKey).slice(0, 8) + '…' : 'n/a'}`,
+        `headers: ${JSON.stringify(Object.keys(request.headers))} | ` +
+        `key prefix: ${apiKey ? String(apiKey).slice(0, 8) + '…' : 'n/a'}`,
     );
 
     if (!apiKey) {
@@ -44,11 +50,15 @@ export class ApiKeyGuard implements CanActivate {
 
     try {
       const keyEntry = await this.apiKeysService.validateKey(apiKey as string);
-      this.logger.log(`[${method} ${url}] accepted – key "${keyEntry.name}" (id=${keyEntry.id})`);
+      this.logger.log(
+        `[${method} ${url}] accepted – key "${keyEntry.name}" (id=${keyEntry.id})`,
+      );
       request.apiKeyMetadata = { id: keyEntry.id, name: keyEntry.name };
       return true;
     } catch (err) {
-      this.logger.warn(`[${method} ${url}] rejected – validation failed: ${err.message}`);
+      this.logger.warn(
+        `[${method} ${url}] rejected – validation failed: ${err.message}`,
+      );
       throw new UnauthorizedException(err.message || 'Invalid API Key');
     }
   }