Shared Spinner component for button loading states

Adds a reusable shadcn-style Spinner (lucide loader-circle icon,
localized aria-label) and wires it into every button that has a
pending state: comment submit, delete, tag save, profile save,
admin saves, upload, login and register.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

app/components/ui/spinner/Spinner.vue

@@ -0,0 +1,17 @@
+<script setup lang="ts">
+import type { HTMLAttributes } from 'vue'
+import { cn } from '@/lib/utils'
+
+const props = defineProps<{
+  class?: HTMLAttributes['class']
+}>()
+</script>
+
+<template>
+  <Icon
+    name="lucide:loader-circle"
+    role="status"
+    :aria-label="$t('common.loading')"
+    :class="cn('size-4 animate-spin', props.class)"
+  />
+</template>

app/components/ui/spinner/index.ts

@@ -0,0 +1 @@
+export { default as Spinner } from './Spinner.vue'