fix(orchestrator): resolve DockerSandboxService DI failure on startup

Add explicit @Inject("DOCKER_CLIENT") token to the Docker constructor
parameter in DockerSandboxService. The @Optional() decorator alone was
not suppressing the NestJS resolution error for the external dockerode
class, causing the orchestrator container to crash on startup.

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

apps/orchestrator/src/spawner/docker-sandbox.service.ts

@@ -1,4 +1,4 @@
-import { Injectable, Logger, Optional } from "@nestjs/common";
+import { Inject, Injectable, Logger, Optional } from "@nestjs/common";
 import { ConfigService } from "@nestjs/config";
 import { randomBytes } from "crypto";
 import Docker from "dockerode";
@@ -86,7 +86,7 @@ export class DockerSandboxService {
 
   constructor(
     private readonly configService: ConfigService,
-    @Optional() docker?: Docker
+    @Optional() @Inject("DOCKER_CLIENT") docker?: Docker
   ) {
     const socketPath = this.configService.get<string>(
       "orchestrator.docker.socketPath",