feat: fullscreen composable, roadmap update, and future plans doc

src/composables/useFullscreen.ts

@@ -0,0 +1,28 @@
+import { ref, onMounted, onUnmounted } from 'vue'
+
+export function useFullscreen() {
+  const isFullscreen = ref(false)
+
+  function sync() {
+    isFullscreen.value = !!document.fullscreenElement
+  }
+
+  async function toggle() {
+    if (!document.fullscreenElement) {
+      await document.documentElement.requestFullscreen().catch(() => {})
+    } else {
+      await document.exitFullscreen()
+    }
+  }
+
+  onMounted(() => {
+    document.addEventListener('fullscreenchange', sync)
+    sync()
+  })
+
+  onUnmounted(() => {
+    document.removeEventListener('fullscreenchange', sync)
+  })
+
+  return { isFullscreen, toggle }
+}