feat(frontend): add LandingFeatures client component with scroll animation

thoughts-frontend/components/landing-features.tsx

@@ -0,0 +1,66 @@
+"use client";
+
+import { useEffect, useRef } from "react";
+
+const FEATURES = [
+  {
+    icon: "✍️",
+    title: "Say it in 128",
+    body: "Short, focused thoughts. No bloat, no essays.",
+  },
+  {
+    icon: "🎨",
+    title: "Make it yours",
+    body: "Customize your profile with CSS. Full creative control.",
+  },
+  {
+    icon: "🔒",
+    title: "Your audience, your rules",
+    body: "Public, followers-only, unlisted, or direct — you decide every time.",
+  },
+  {
+    icon: "🎬",
+    title: "Movies Diary",
+    body: "Posts from your Movies Diary appear as rich cards — ratings, posters, reviews. First-class, not an afterthought.",
+  },
+];
+
+export function LandingFeatures() {
+  const ref = useRef<HTMLDivElement>(null);
+
+  useEffect(() => {
+    const cards = Array.from(
+      ref.current?.querySelectorAll("[data-animate]") ?? []
+    );
+    const observer = new IntersectionObserver(
+      (entries) => {
+        entries.forEach((entry) => {
+          if (entry.isIntersecting) {
+            entry.target.classList.add("visible");
+            observer.unobserve(entry.target);
+          }
+        });
+      },
+      { threshold: 0.15 }
+    );
+    cards.forEach((card) => observer.observe(card));
+    return () => observer.disconnect();
+  }, []);
+
+  return (
+    <div ref={ref} className="grid grid-cols-1 sm:grid-cols-2 gap-4 mt-8">
+      {FEATURES.map((f, i) => (
+        <div
+          key={f.title}
+          data-animate
+          className="landing-card-animate glass-effect rounded-xl p-6 shadow-fa-md"
+          style={{ animationDelay: `${i * 100}ms` }}
+        >
+          <div className="text-3xl mb-3">{f.icon}</div>
+          <h3 className="font-bold text-base mb-1">{f.title}</h3>
+          <p className="text-sm text-muted-foreground">{f.body}</p>
+        </div>
+      ))}
+    </div>
+  );
+}