fix: exempt health endpoint from rate limiting

Docker/load-balancer health probes hit GET /health every ~5s from
127.0.0.1, exhausting the rate limit and causing all subsequent checks
to return 429 — making the service appear unhealthy.

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

apps/api/src/app.controller.ts

@@ -1,4 +1,5 @@
 import { Controller, Get } from "@nestjs/common";
+import { SkipThrottle } from "@nestjs/throttler";
 import { AppService } from "./app.service";
 import { PrismaService } from "./prisma/prisma.service";
 import type { ApiResponse, HealthStatus } from "@mosaic/shared";
@@ -17,6 +18,7 @@ export class AppController {
   }
 
   @Get("health")
+  @SkipThrottle()
   async getHealth(): Promise<ApiResponse<HealthStatus>> {
     const dbHealthy = await this.prisma.isHealthy();
     const dbInfo = await this.prisma.getConnectionInfo();