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>

packages/config/prettier/index.js

@@ -0,0 +1,13 @@
+/** @type {import("prettier").Config} */
+const config = {
+  semi: true,
+  singleQuote: false,
+  tabWidth: 2,
+  trailingComma: "es5",
+  printWidth: 100,
+  bracketSpacing: true,
+  arrowParens: "always",
+  endOfLine: "lf",
+};
+
+export default config;