feat(05-02): add Columns/Details/Video/Badge MDC components + full showcase article

app/components/content/Badge.vue

@@ -0,0 +1,27 @@
+<script setup lang="ts">
+interface Props {
+  color?: 'gray' | 'blue' | 'green' | 'red' | 'yellow' | 'purple' | 'orange'
+}
+const props = withDefaults(defineProps<Props>(), { color: 'gray' })
+
+const colorClass = {
+  gray: 'bg-neutral-100 text-neutral-700 dark:bg-neutral-800 dark:text-neutral-300',
+  blue: 'bg-blue-100 text-blue-700 dark:bg-blue-900/40 dark:text-blue-300',
+  green: 'bg-emerald-100 text-emerald-700 dark:bg-emerald-900/40 dark:text-emerald-300',
+  red: 'bg-red-100 text-red-700 dark:bg-red-900/40 dark:text-red-300',
+  yellow: 'bg-amber-100 text-amber-700 dark:bg-amber-900/40 dark:text-amber-300',
+  purple: 'bg-violet-100 text-violet-700 dark:bg-violet-900/40 dark:text-violet-300',
+  orange: 'bg-orange-100 text-orange-700 dark:bg-orange-900/40 dark:text-orange-300',
+}
+</script>
+
+<template>
+  <span
+    :class="[
+      'inline-flex items-center rounded-full px-2 py-0.5 text-xs font-medium font-mono',
+      colorClass[props.color],
+    ]"
+  >
+    <slot />
+  </span>
+</template>