Apply UI updates: tags gap, notifications, card click, breadcrumb, move share input

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/components/NotificationCenter.tsx

@@ -0,0 +1,22 @@
+import React from 'react'
+import useAppStore from '../store/useAppStore'
+
+const NotificationCenter: React.FC = () => {
+  const notifications = useAppStore((s) => s.notifications)
+  const removeNotification = useAppStore((s) => s.removeNotification)
+
+  if (!notifications || notifications.length === 0) return null
+
+  return (
+    <div className="notif-container">
+      {notifications.map((n) => (
+        <div key={n.id} className={`notif ${n.type ?? ''}`}>
+          <div>{n.message}</div>
+          <button onClick={() => removeNotification(n.id)}>×</button>
+        </div>
+      ))}
+    </div>
+  )
+}
+
+export default NotificationCenter