feat(notes): wire app with floating add button

src/components/FloatingButton.tsx

@@ -0,0 +1,19 @@
+interface FloatingButtonProps {
+  onClick: () => void
+  label?: string
+}
+
+function FloatingButton({ onClick, label = 'Créer une note' }: FloatingButtonProps) {
+  return (
+    <button
+      type="button"
+      onClick={onClick}
+      aria-label={label}
+      className="fixed bottom-6 right-6 w-14 h-14 rounded-full bg-amber-400 text-3xl text-gray-800 shadow-lg active:scale-95"
+    >
+      +
+    </button>
+  )
+}
+
+export default FloatingButton