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/lib/hooks/useFollows.ts

@@ -1,11 +1,14 @@
 import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
 import { followsAPI } from "../api";
+import { useAuthStore } from "@/stores/authStore";
 
 export function useFollows() {
+  const token = useAuthStore((s) => s.token);
   return useQuery({
     queryKey: ["follows"],
     queryFn: () => followsAPI.list(),
     staleTime: 30 * 1000,
+    enabled: !!token,
   });
 }
 
@@ -14,7 +17,10 @@ export function useAddFollow() {
   return useMutation({
     mutationFn: ({ type, value }: { type: string; value: string }) =>
       followsAPI.add(type, value),
-    onSuccess: () => qc.invalidateQueries({ queryKey: ["follows"] }),
+    onSuccess: () => {
+      qc.invalidateQueries({ queryKey: ["follows"] });
+      qc.invalidateQueries({ queryKey: ["dashboard"] });
+    },
   });
 }
 
@@ -22,7 +28,10 @@ export function useRemoveFollow() {
   const qc = useQueryClient();
   return useMutation({
     mutationFn: (id: number) => followsAPI.remove(id),
-    onSuccess: () => qc.invalidateQueries({ queryKey: ["follows"] }),
+    onSuccess: () => {
+      qc.invalidateQueries({ queryKey: ["follows"] });
+      qc.invalidateQueries({ queryKey: ["dashboard"] });
+    },
   });
 }