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/src/app/globals.css

@@ -0,0 +1,20 @@
+@tailwind base;
+@tailwind components;
+@tailwind utilities;
+
+:root {
+  --foreground-rgb: 0, 0, 0;
+  --background-rgb: 255, 255, 255;
+}
+
+@media (prefers-color-scheme: dark) {
+  :root {
+    --foreground-rgb: 255, 255, 255;
+    --background-rgb: 0, 0, 0;
+  }
+}
+
+body {
+  color: rgb(var(--foreground-rgb));
+  background: rgb(var(--background-rgb));
+}