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/web/package.json

@@ -0,0 +1,36 @@
+{
+  "name": "@mosaic/web",
+  "version": "0.0.1",
+  "private": true,
+  "scripts": {
+    "build": "next build",
+    "dev": "next dev --turbopack --port 3000",
+    "start": "next start",
+    "lint": "next lint",
+    "lint:fix": "next lint --fix",
+    "typecheck": "tsc --noEmit",
+    "clean": "rm -rf .next",
+    "test": "vitest run",
+    "test:watch": "vitest",
+    "test:coverage": "vitest run --coverage"
+  },
+  "dependencies": {
+    "@mosaic/shared": "workspace:*",
+    "@mosaic/ui": "workspace:*",
+    "next": "^16.1.6",
+    "react": "^19.0.0",
+    "react-dom": "^19.0.0"
+  },
+  "devDependencies": {
+    "@mosaic/config": "workspace:*",
+    "@testing-library/jest-dom": "^6.6.3",
+    "@testing-library/react": "^16.2.0",
+    "@types/node": "^22.13.4",
+    "@types/react": "^19.0.8",
+    "@types/react-dom": "^19.0.3",
+    "@vitejs/plugin-react": "^4.3.4",
+    "jsdom": "^26.0.0",
+    "typescript": "^5.8.2",
+    "vitest": "^3.0.8"
+  }
+}