feat(p9): request-scoped trace context + middleware + structured logger

Task O.1: AsyncLocalStorage trace context (currentTraceId/runWithTrace/toTraceparent)
read by singleton services with no DI churn; Express traceMiddleware derives a trace
id per request (x-trace-id → traceparent → generated), echoes x-trace-id on the
response, runs the request in-context, and logs a structured http.request line on
finish. Minimal JSON structured logger stamps traceId on every line. Wired via
app.use in main.ts. 4 tests: scope, concurrency isolation, traceparent shape/parse.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/iios-service/src/main.ts

@@ -3,9 +3,11 @@ import 'reflect-metadata';
 import { NestFactory } from '@nestjs/core';
 import { ValidationPipe } from '@nestjs/common';
 import { AppModule } from './app.module';
+import { traceMiddleware } from './observability/trace.middleware';
 
 async function bootstrap(): Promise<void> {
   const app = await NestFactory.create(AppModule, { rawBody: true });
+  app.use(traceMiddleware); // request-scoped trace context + x-trace-id header (P9)
   app.useGlobalPipes(
     new ValidationPipe({ whitelist: true, forbidNonWhitelisted: true, transform: true }),
   );