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.controller.d.ts

@@ -0,0 +1,14 @@
+import { AppService } from "./app.service";
+import type { ApiResponse } from "@mosaic/shared/types";
+interface HealthStatus {
+    status: string;
+    timestamp: string;
+}
+export declare class AppController {
+    private readonly appService;
+    constructor(appService: AppService);
+    getHello(): string;
+    getHealth(): ApiResponse<HealthStatus>;
+}
+export {};
+//# sourceMappingURL=app.controller.d.ts.map