Add SettingsModal component and integrate with App.vue

- Introduced `SettingsModal.vue` for managing user settings with a responsive dialog interface.
- Updated `App.vue` to include `SettingsModal` and support easy access to settings.
- Removed outdated form implementation in `SettingsScreen.vue` to streamline settings handling.

src/screens/SettingsScreen.vue

@@ -1,22 +1,9 @@
 <script setup lang="ts">
-import { useSettings } from '../composables/useSettings.ts';
 
-const { settings } = useSettings();
 </script>
 
 <template>
-<div>
-  <form>
-    <fieldset class="fieldset">
-      <legend class="fieldset-legend">Username</legend>
-      <input v-model="settings.username" type="text" class="input" name="username" />
-    </fieldset>
-    <fieldset class="fieldset">
-      <legend class="fieldset-legend">Password</legend>
-      <input v-model="settings.password" type="text" class="input" name="password" />
-    </fieldset>
-  </form>
-</div>
+  <div />
 </template>
 
 <style scoped>