refactor: update color modes handling

src/App.vue

@@ -1,6 +1,34 @@
 <template>
   <router-view />
 </template>
+<script>
+import { onBeforeMount } from 'vue'
+import { useStore } from 'vuex'
+import { useColorModes } from '@coreui/vue'
+
+export default {
+  setup() {
+    const { isColorModeSet, setColorMode } = useColorModes(
+      'coreui-free-vue-admin-template-theme',
+    )
+    const store = useStore()
+
+    onBeforeMount(() => {
+      const urlParams = new URLSearchParams(window.location.href.split('?')[1])
+      if (urlParams.get('theme')) {
+        setColorMode(urlParams.get('theme'))
+        return
+      }
+
+      if (isColorModeSet()) {
+        return
+      }
+
+      setColorMode(store.state.theme)
+    })
+  },
+}
+</script>
 
 <style lang="scss">
 // Import Main styles for this application