fix(SEC-ORCH-16): Implement real health and readiness checks

- Add ping() method to ValkeyClient and ValkeyService for health checks
- Update HealthService to check Valkey connectivity before reporting ready
- /health/ready now returns 503 if dependencies are unhealthy
- Add detailed checks object showing individual dependency status
- Update tests with ValkeyService mock

Refs #339

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

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

@@ -1,6 +1,6 @@
-import { Controller, Get, UseGuards } from "@nestjs/common";
+import { Controller, Get, UseGuards, HttpStatus, HttpException } from "@nestjs/common";
 import { Throttle } from "@nestjs/throttler";
-import { HealthService } from "./health.service";
+import { HealthService, ReadinessResult } from "./health.service";
 import { OrchestratorThrottlerGuard } from "../../common/guards/throttler.guard";
 
 /**
@@ -26,8 +26,13 @@ export class HealthController {
 
   @Get("ready")
   @Throttle({ status: { limit: 200, ttl: 60000 } })
-  ready(): { ready: boolean } {
-    // NOTE: Check Valkey connection, Docker daemon (see issue #TBD)
-    return { ready: true };
+  async ready(): Promise<ReadinessResult> {
+    const result = await this.healthService.isReady();
+
+    if (!result.ready) {
+      throw new HttpException(result, HttpStatus.SERVICE_UNAVAILABLE);
+    }
+
+    return result;
   }
 }