feat(public_page): allow unauthenticated browsing with auth-gated interactivity

- Add get_optional_user dependency; dashboard returns guest-safe payload
- AuthGuard only redirects /following and /notifications for guests
- Sidebar hides auth-required nav items and shows Sign In/Register for guests
- Dashboard shows trending bills as "Most Popular" for unauthenticated visitors
- FollowButton opens AuthModal instead of acting when not signed in
- Members page pins followed members at the top for quick unfollowing
- useFollows skips API call and invalidates dashboard on follow/unfollow

Authored-By: Jack Levy

frontend/components/shared/AuthGuard.tsx

@@ -6,7 +6,8 @@ import { useAuthStore } from "@/stores/authStore";
 import { Sidebar } from "./Sidebar";
 import { MobileHeader } from "./MobileHeader";
 
-const PUBLIC_PATHS = ["/login", "/register"];
+const NO_SHELL_PATHS = ["/login", "/register"];
+const AUTH_REQUIRED = ["/following", "/notifications"];
 
 export function AuthGuard({ children }: { children: React.ReactNode }) {
   const router = useRouter();
@@ -22,22 +23,24 @@ export function AuthGuard({ children }: { children: React.ReactNode }) {
 
   useEffect(() => {
     if (!hydrated) return;
-    if (!token && !PUBLIC_PATHS.includes(pathname)) {
+    const needsAuth = AUTH_REQUIRED.some((p) => pathname.startsWith(p));
+    if (!token && needsAuth) {
       router.replace("/login");
     }
   }, [hydrated, token, pathname, router]);
 
   if (!hydrated) return null;
 
-  // Public pages (login/register) render without the app shell
-  if (PUBLIC_PATHS.includes(pathname)) {
+  // Login/register pages render without the app shell
+  if (NO_SHELL_PATHS.includes(pathname)) {
     return <>{children}</>;
   }
 
-  // Not logged in yet — blank while redirecting
-  if (!token) return null;
+  // Auth-required pages: blank while redirecting
+  const needsAuth = AUTH_REQUIRED.some((p) => pathname.startsWith(p));
+  if (!token && needsAuth) return null;
 
-  // Authenticated: render the full app shell
+  // Authenticated or guest browsing: render the full app shell
   return (
     <div className="flex h-screen bg-background">
       {/* Desktop sidebar — hidden on mobile */}