feat: add message editing

This commit adds message editing as a feature. To accomplish this, the settings
dialog was refactored into a singleton and now the message edit and settings
use the singleton where appropriate.

app/layouts/default.vue

@@ -1,5 +1,5 @@
 <script setup lang="ts">
-import SettingsDialog from '~/components/Settings/Dialog.vue';
+import Dialog from '~/components/Dialog/index.vue';
 
 const { colorScheme } = await useUserSettings();
 
@@ -20,6 +20,8 @@ useKeyboardShortcuts();
             <slot />
         </div>
     </main>
-    <SettingsDialog />
-    <Dropdown />
+    <ClientOnly>
+        <Dialog />
+        <Dropdown />
+    </ClientOnly>
 </template>