Refactor frontend components and enhance API integration

- Updated frontend-nuxt.mdc to specify usage of composables for API calls.
- Added new AuthCard and ConfirmModal components for improved UI consistency.
- Introduced UserAvatar component for user profile display, replacing previous Gravatar implementation.
- Implemented useFormSubmit composable for handling form submissions with loading and error states.
- Enhanced vitest.config.ts to include coverage reporting for composables and components.
- Removed deprecated useAdminApi and useAuth composables to streamline API interactions.
- Updated login and setup pages to utilize new components and composables for better user experience.

frontend-nuxt/components/UserAvatar.vue

@@ -0,0 +1,42 @@
+<template>
+  <div class="avatar">
+    <div
+      class="rounded-full overflow-hidden flex items-center justify-center shrink-0"
+      :style="{ width: `${size}px`, height: `${size}px` }"
+    >
+      <img
+        v-if="email && !gravatarError"
+        :src="useGravatarUrl(email, size)"
+        alt=""
+        class="w-full h-full object-cover"
+        @error="gravatarError = true"
+      >
+      <div
+        v-else
+        class="bg-primary text-primary-content rounded-full w-full h-full flex items-center justify-center"
+        :class="initialClass"
+      >
+        <span>{{ (username || '?')[0].toUpperCase() }}</span>
+      </div>
+    </div>
+  </div>
+</template>
+
+<script setup lang="ts">
+const props = withDefaults(
+  defineProps<{
+    username: string
+    email?: string
+    size?: number
+  }>(),
+  { size: 32 }
+)
+
+const gravatarError = ref(false)
+
+const initialClass = computed(() => {
+  if (props.size <= 32) return 'text-sm'
+  if (props.size <= 40) return 'text-sm'
+  return 'text-2xl font-semibold'
+})
+</script>