feat: initialize monorepo structure with Bun and Turborepo

- Add package.json for the root with workspace configuration and scripts
- Create @gruperly/config package with TypeScript configuration
- Establish shared package @gruperly/shared with Zod schemas for validation
- Implement group, student, and payment schemas using Zod
- Set up TypeScript configuration for shared package
- Document stack architecture and technical specifications in stack.md
- Configure Turborepo with build, dev, lint, and typecheck tasks

apps/web/src/routes/home.tsx

@@ -0,0 +1,8 @@
+export function HomeView() {
+  return (
+    <section>
+      <h1 className="text-2xl font-bold text-primary">Inicio</h1>
+      <p className="mt-2 text-sm text-foreground/60">Bienvenido a Gruperly.</p>
+    </section>
+  )
+}