feat: visual polish & UX — fade-in, theme toggle, scroll-to-top, footer, cursor, badge

- Add FadeIn component (IntersectionObserver scroll-reveal + load animation)
- Add dark/light theme toggle (useSyncExternalStore + localStorage)
- Add scroll-to-top button (appears after 300px scroll)
- Add configurable footer with social links (gallery.yaml)
- Add crosshair cursor on photo grid items
- Add 'X photos' count badge on subpage cover images
- Add light theme color palette in tokens.css

app/api/auth/route.ts

@@ -7,40 +7,25 @@ import { NextRequest, NextResponse } from 'next/server';
 import { authenticate, isProtected } from '@/lib/auth';
 
 export async function POST(request: NextRequest) {
-    try {
-        const body = await request.json();
-        const { slug, password } = body;
+  try {
+    const body = await request.json();
+    const { slug, password } = body;
 
-        if (!slug || !password) {
-            return NextResponse.json(
-                { error: 'Missing slug or password' },
-                { status: 400 },
-            );
-        }
-
-        if (!isProtected(slug)) {
-            return NextResponse.json(
-                { error: 'Album is not password-protected' },
-                { status: 400 },
-            );
-        }
-
-        const setCookie = authenticate(slug, password);
-        if (!setCookie) {
-            return NextResponse.json(
-                { error: 'Invalid password' },
-                { status: 401 },
-            );
-        }
-
-        return NextResponse.json(
-            { success: true },
-            { headers: { 'Set-Cookie': setCookie } },
-        );
-    } catch {
-        return NextResponse.json(
-            { error: 'Invalid request body' },
-            { status: 400 },
-        );
+    if (!slug || !password) {
+      return NextResponse.json({ error: 'Missing slug or password' }, { status: 400 });
     }
+
+    if (!isProtected(slug)) {
+      return NextResponse.json({ error: 'Album is not password-protected' }, { status: 400 });
+    }
+
+    const setCookie = authenticate(slug, password);
+    if (!setCookie) {
+      return NextResponse.json({ error: 'Invalid password' }, { status: 401 });
+    }
+
+    return NextResponse.json({ success: true }, { headers: { 'Set-Cookie': setCookie } });
+  } catch {
+    return NextResponse.json({ error: 'Invalid request body' }, { status: 400 });
+  }
 }