feat: Wire NATS command publishing for server commands and plugin installs

- servers.service: sendCommand() now throws InternalServerErrorException on
  NATS failure instead of silently succeeding; returns { success, message }
  instead of the legacy { output } shape; adds NestJS Logger
- plugins.service: installPlugin() dispatches plugin_install to
  corrosion.{license_id}.cmd.server after DB save; NATS failure is logged
  but non-fatal so the DB record is preserved regardless

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

backend-nest/src/modules/servers/servers.service.ts

@@ -1,4 +1,4 @@
-import { Injectable, NotFoundException } from '@nestjs/common';
+import { Injectable, NotFoundException, InternalServerErrorException, Logger } from '@nestjs/common';
 import { InjectRepository } from '@nestjs/typeorm';
 import { Repository } from 'typeorm';
 import { ServerConnection } from '../../entities/server-connection.entity';
@@ -9,6 +9,8 @@ import { DeployServerDto } from './dto/deploy-server.dto';
 
 @Injectable()
 export class ServersService {
+  private readonly logger = new Logger(ServersService.name);
+
   constructor(
     @InjectRepository(ServerConnection)
     private readonly connectionRepo: Repository<ServerConnection>,
@@ -60,8 +62,14 @@ export class ServersService {
    * Send a console command to the server via NATS
    */
   async sendCommand(licenseId: string, command: string) {
-    await this.natsService.sendServerCommand(licenseId, 'command', { command });
-    return { output: 'Command sent' };
+    try {
+      await this.natsService.sendServerCommand(licenseId, 'command', { command });
+      this.logger.log(`Console command dispatched for license ${licenseId}: ${command}`);
+    } catch (err) {
+      this.logger.error(`Failed to dispatch console command for license ${licenseId}: ${(err as Error).message}`);
+      throw new InternalServerErrorException('Failed to dispatch command to server');
+    }
+    return { success: true, message: 'Command dispatched' };
   }
 
   /**