feat(#1): Set up monorepo scaffold with pnpm workspaces + TurboRepo

Implements the foundational project structure including:
- pnpm workspaces configuration
- TurboRepo for build orchestration
- NestJS 11.1.12 API (apps/api)
- Next.js 16.1.6 web app (apps/web)
- Shared packages (config, shared, ui)
- TypeScript strict mode configuration
- ESLint + Prettier setup
- Vitest for unit testing (19 passing tests)

Fixes #1

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

apps/api/src/app.module.ts

@@ -0,0 +1,10 @@
+import { Module } from "@nestjs/common";
+import { AppController } from "./app.controller";
+import { AppService } from "./app.service";
+
+@Module({
+  imports: [],
+  controllers: [AppController],
+  providers: [AppService],
+})
+export class AppModule {}