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/app/page.tsx

@@ -1,14 +1,17 @@
 "use client";
 
-import { TrendingUp, BookOpen, RefreshCw } from "lucide-react";
+import { TrendingUp, BookOpen, Flame, RefreshCw } from "lucide-react";
+import Link from "next/link";
 import { useDashboard } from "@/lib/hooks/useDashboard";
 import { BillCard } from "@/components/shared/BillCard";
 import { adminAPI } from "@/lib/api";
 import { useState } from "react";
+import { useAuthStore } from "@/stores/authStore";
 
 export default function DashboardPage() {
   const { data, isLoading, refetch } = useDashboard();
   const [polling, setPolling] = useState(false);
+  const token = useAuthStore((s) => s.token);
 
   const triggerPoll = async () => {
     setPolling(true);
@@ -43,15 +46,38 @@ export default function DashboardPage() {
         <div className="grid grid-cols-1 md:grid-cols-3 gap-4 md:gap-8">
           <div className="md:col-span-2 space-y-4">
             <h2 className="font-semibold flex items-center gap-2">
-              <BookOpen className="w-4 h-4" />
-              Your Feed
-              {data?.follows && (
+              {token ? <BookOpen className="w-4 h-4" /> : <Flame className="w-4 h-4" />}
+              {token ? "Your Feed" : "Most Popular"}
+              {token && data?.follows && (
                 <span className="text-xs text-muted-foreground font-normal">
                   ({data.follows.bills} bills · {data.follows.members} members · {data.follows.topics} topics)
                 </span>
               )}
             </h2>
-            {!data?.feed?.length ? (
+            {!token ? (
+              <div className="space-y-3">
+                <div className="rounded-lg border border-dashed px-4 py-3 flex items-center justify-between gap-4">
+                  <p className="text-sm text-muted-foreground">
+                    Sign in to personalise this feed with bills and members you follow.
+                  </p>
+                  <div className="flex gap-2 shrink-0">
+                    <Link href="/register" className="px-3 py-1.5 text-xs font-medium rounded-md bg-primary text-primary-foreground hover:bg-primary/90 transition-colors">
+                      Register
+                    </Link>
+                    <Link href="/login" className="px-3 py-1.5 text-xs font-medium rounded-md border border-border text-foreground hover:bg-accent transition-colors">
+                      Sign in
+                    </Link>
+                  </div>
+                </div>
+                {data?.trending?.length ? (
+                  <div className="space-y-3">
+                    {data.trending.map((bill) => (
+                      <BillCard key={bill.bill_id} bill={bill} />
+                    ))}
+                  </div>
+                ) : null}
+              </div>
+            ) : !data?.feed?.length ? (
               <div className="bg-card border border-border rounded-lg p-8 text-center text-muted-foreground">
                 <p className="text-sm">Your feed is empty.</p>
                 <p className="text-xs mt-1">Follow bills, members, or topics to see activity here.</p>