Add first version of the frontend

As of now the only usable functionality is signin in/out and managing
authorized users, and even then there is much room for improvement.

Change-Id: Ib87fc6866f69113a230187710de8644b78391917
diff --git a/frontend/src/pages/NotAuthorized.vue b/frontend/src/pages/NotAuthorized.vue
new file mode 100644
index 0000000..f0b0a49
--- /dev/null
+++ b/frontend/src/pages/NotAuthorized.vue
@@ -0,0 +1,38 @@
+<script>
+import Page from './utils/Page.vue';
+
+export default {
+  components: {
+    Page,
+  },
+};
+</script>
+
+<template>
+  <page mini>
+    <div class="layout">
+      <mcw-material-icon class="main-icon" icon="no_accounts" />
+      <span class="label">You're not signed in.</span>
+    </div>
+  </page>
+</template>
+
+<style lang="scss" scoped>
+@use "@material/theme/color-palette" as palette;
+
+.layout {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  margin: 16px 0;
+}
+
+.main-icon {
+  font-size: 75px;
+  color: palette.$grey-800;
+}
+
+.label {
+  margin-top: 14px;
+}
+</style>