feat(wrapped-ui): 引入多主题系统与切换器（Modern/Game Boy/DOS/VHS）

- 新增 useWrappedTheme：主题状态全局共享、localStorage 持久化，支持 F1-F4 快捷键与循环切换

- 新增主题切换器组件（Modern/Game Boy/DOS/VHS）与主题化年份选择器

- 年度总结页接入 themeClass/currentBg；CRT 叠加层支持 VHS 效果（REC/时间戳/跟踪线）

- 补充主题全局样式与卡片/控制面板主题适配

frontend/components/wrapped/shared/WrappedThemeSwitcherModern.vue

@@ -0,0 +1,31 @@
+<template>
+  <div class="flex items-center gap-2">
+    <span class="text-xs text-[#00000099]">Theme</span>
+    <div class="inline-flex rounded-lg border border-[#EDEDED] overflow-hidden">
+      <button
+        v-for="t in themes"
+        :key="t.value"
+        class="px-3 py-1.5 text-xs wrapped-label transition-colors"
+        :class="[
+          theme === t.value
+            ? 'bg-[#07C160] text-white'
+            : 'bg-white text-[#333] hover:bg-[#F5F5F5]'
+        ]"
+        @click="setTheme(t.value)"
+      >
+        {{ t.label }}
+      </button>
+    </div>
+  </div>
+</template>
+
+<script setup>
+const { theme, setTheme, VALID_THEMES } = useWrappedTheme()
+
+const themes = [
+  { value: 'off', label: 'Modern' },
+  { value: 'gameboy', label: 'Game Boy' },
+  { value: 'dos', label: 'DOS' },
+  { value: 'vhs', label: 'VHS' }
+]
+</script>