chore: upgrade to nuxt 4

app/components/ColourPicker.vue

@@ -0,0 +1,99 @@
+<script setup lang="ts">
+import IconSun from "@/assets/images/sun.svg?component";
+import IconMoon from "@/assets/images/moon.svg?component";
+
+const colorMode = useColorMode();
+
+const toggle = () => {
+  colorMode.preference = colorMode.value === "light" ? "dark" : "light";
+};
+</script>
+
+<template>
+  <label
+    for="dark-toggle"
+    class="toggle-wrapper"
+    aria-label="Dark mode indicator label"
+  >
+    <div class="toggle">
+      <div class="icons">
+        <IconMoon />
+        <IconSun />
+      </div>
+      <input
+        id="dark-toggle"
+        name="dark-toggle"
+        type="checkbox"
+        ref="darkToggleEl"
+        aria-label="Toggle dark mode"
+        @click="toggle"
+      />
+    </div>
+  </label>
+</template>
+
+<style scoped>
+.toggle-wrapper {
+  width: 6rem;
+  display: block;
+  --black: #333333;
+  --white: #f5f5f5;
+  --scale: 2rem;
+  --transition: 0.2s ease;
+  --bg: var(--white);
+  --fg: var(--black);
+}
+
+html.dark .toggle-wrapper {
+  --black: #f5f5f5;
+  --white: #333333;
+}
+
+.toggle {
+  height: var(--scale);
+  width: calc(var(--scale) * 2);
+  background: var(--fg);
+  border-radius: var(--scale);
+  padding: calc(var(--scale) * 0.175);
+  position: relative;
+  margin: auto;
+  cursor: pointer;
+  transition: background var(--transition);
+}
+
+.toggle::before {
+  content: "";
+  display: block;
+  height: calc(var(--scale) * 0.65);
+  width: calc(var(--scale) * 0.65);
+  border-radius: 50%;
+  background: var(--bg);
+  position: absolute;
+  z-index: 2;
+  transform: translate(0);
+  transition: transform var(--transition), background var(--transition);
+}
+
+html.dark .toggle::before {
+  transform: translateX(calc(var(--scale)));
+}
+
+.toggle input {
+  position: absolute;
+  top: 0;
+  opacity: 0;
+}
+
+.toggle .icons {
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+  height: 100%;
+}
+
+.toggle .icons svg {
+  transform: scale(0.7);
+  z-index: 0;
+  fill: var(--bg);
+}
+</style>