feat: add Agrarmonitor integration module

- New backend module (agrarmonitor) with status check and device registration
- Frontend settings tab with connection status display and registration form
- Environment variables for base URLs, credentials, cookie path and encryption key
- Docker Compose env passthrough for agrarmonitor config

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

paperless-backend/src/agrarmonitor/agrarmonitor.module.ts

@@ -0,0 +1,10 @@
+import { Module } from '@nestjs/common';
+import { AgrarmonitorService } from './agrarmonitor.service';
+import { AgrarmonitorController } from './agrarmonitor.controller';
+
+@Module({
+  providers: [AgrarmonitorService],
+  controllers: [AgrarmonitorController],
+  exports: [AgrarmonitorService],
+})
+export class AgrarmonitorModule {}