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/package.json

@@ -9,11 +9,13 @@
     "type-check": "tsc --noEmit"
   },
   "dependencies": {
+    "jose": "^6.2.3",
     "next": "^15.3.0",
     "next-intl": "^4.13.0",
     "next-themes": "^0.4.6",
     "react": "^19.0.0",
     "react-dom": "^19.0.0",
+    "zod": "^4.4.3",
     "zustand": "^5.0.14"
   },
   "devDependencies": {