feat(02-02): auth infrastructure -- route groups, middleware, session, auth-actions, auth store

- Create (auth) route group with standalone layout (no sidebar/header, D-04)
- Create (portal) route group wrapping children with AppShell
- Move dashboard page into (portal) route group
- Add Next.js middleware for JWT-based route protection using jose
- Create session.ts with verifySession/getSessionFromCookies helpers
- Create auth-actions.ts server actions: login, logout, fetchCurrentUser
- Create Zustand auth-store for client-side user state
- Install jose and zod dependencies

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/web/src/app/(auth)/layout.tsx

@@ -0,0 +1,15 @@
+/**
+ * Auth layout - standalone, no sidebar/header (D-04).
+ * Used for /login, /reset-password, etc.
+ */
+export default function AuthLayout({
+  children,
+}: {
+  children: React.ReactNode;
+}) {
+  return (
+    <div className="min-h-screen bg-background">
+      {children}
+    </div>
+  );
+}