feat(M6): Set up orchestrator service foundation

Add NestJS-based orchestrator service structure for M6-AgentOrchestration.

Changes:
- Migrate from Express to NestJS architecture
- Add health check endpoint module
- Add placeholder modules: coordinator, git, killswitch, monitor, queue, spawner, valkey
- Update configuration for NestJS
- Update lockfile for new dependencies

This is foundational work for M6-AgentOrchestration milestone.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

apps/orchestrator/src/api/health/health.controller.ts

@@ -0,0 +1,20 @@
+import { Controller, Get } from "@nestjs/common";
+
+@Controller("health")
+export class HealthController {
+  @Get()
+  check() {
+    return {
+      status: "ok",
+      service: "orchestrator",
+      version: "0.0.6",
+      timestamp: new Date().toISOString(),
+    };
+  }
+
+  @Get("ready")
+  ready() {
+    // TODO: Check Valkey connection, Docker daemon
+    return { ready: true };
+  }
+}

apps/orchestrator/src/api/health/health.module.ts

@@ -0,0 +1,7 @@
+import { Module } from "@nestjs/common";
+import { HealthController } from "./health.controller";
+
+@Module({
+  controllers: [HealthController],
+})
+export class HealthModule {}