feat(sidebar): show user info with three-state UI (guest/member/vip)

Sidebar screen now primarily displays user-related information
and derives three render states from loginStatus + currentUser.isVip:

- guest (notLoggedIn): welcome panel + Sign in / Sign up entries
- member (logged in, no VIP): user info card + Get VIP CTA + Log out
- vip (logged in, VIP): user info card with VIP badge + Manage VIP CTA
  + Log out

Adds UserView.isVip (default false), patches user-machine.toView()
to populate it, and introduces three presentational components
(GuestPanel, UserInfoCard, VipCta) co-located under src/app/sidebar.

Preserves existing UserInit + logout-redirect behavior.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/stores/user/user-machine.ts

@@ -49,6 +49,7 @@ function toView(u: {
   relationshipStage?: string;
   currentMood?: string;
   isGuest?: boolean;
+  isVip?: boolean;
 }): UserView {
   return {
     id: u.id,
@@ -60,6 +61,7 @@ function toView(u: {
     relationshipStage: u.relationshipStage ?? "",
     currentMood: u.currentMood ?? "",
     isGuest: u.isGuest ?? false,
+    isVip: u.isVip ?? false,
   };
 }