feat(wrapped-ui): 新增 Win98 主题与桌面化外观

- 主题系统新增 win98（显示名 Windows 98，快捷键扩展到 F1-F4），并区分 retro(pixel/CRT) 与桌面 GUI 主题
- 年度总结页新增 Win98 桌面背景与底部任务栏（背景色/视口高度适配）
- 封面与卡片 slide 形态支持 Win98 窗口外观（title bar/icon/controls）
- 主题切换器补充 Win98 选项并新增 Win98 专属切换器
- 新增 Win98 图标资源（Start + 桌面图标）

frontend/components/wrapped/shared/WrappedWin98Taskbar.vue

@@ -0,0 +1,169 @@
+<template>
+  <div class="win98-taskbar" @wheel.stop.prevent>
+    <button
+      type="button"
+      class="win98-start"
+      aria-label="Start"
+      :aria-pressed="startPressed ? 'true' : 'false'"
+      @mousedown="startPressed = true"
+      @mouseup="startPressed = false"
+      @mouseleave="startPressed = false"
+    >
+      <img class="win98-start__icon" src="/assets/images/windows-0.png" alt="" aria-hidden="true" />
+      <span class="win98-start__text">Start</span>
+    </button>
+
+    <div class="win98-taskbar__divider" aria-hidden="true"></div>
+
+    <button
+      type="button"
+      class="win98-task"
+      :title="title"
+      tabindex="-1"
+      aria-label="Active window"
+    >
+      {{ title }}
+    </button>
+
+    <div class="win98-taskbar__spacer" aria-hidden="true"></div>
+
+    <div class="win98-tray" aria-label="System tray">
+      <div class="win98-tray__clock" :title="timeText">
+        {{ timeText }}
+      </div>
+    </div>
+  </div>
+</template>
+
+<script setup>
+import { onBeforeUnmount, onMounted, ref } from 'vue'
+
+defineProps({
+  title: { type: String, default: 'WeChat Wrapped' }
+})
+
+const startPressed = ref(false)
+const timeText = ref('--:--')
+let timer = null
+
+const formatWin98Time = (d) => {
+  try {
+    // Win98 screenshot style: 12-hour + AM/PM
+    return new Intl.DateTimeFormat('en-US', { hour: 'numeric', minute: '2-digit' }).format(d)
+  } catch {
+    const hh = String(d.getHours()).padStart(2, '0')
+    const mm = String(d.getMinutes()).padStart(2, '0')
+    return `${hh}:${mm}`
+  }
+}
+
+const updateClock = () => { timeText.value = formatWin98Time(new Date()) }
+
+onMounted(() => {
+  updateClock()
+  timer = setInterval(updateClock, 30_000)
+})
+
+onBeforeUnmount(() => {
+  if (timer) clearInterval(timer)
+  timer = null
+})
+</script>
+
+<style scoped>
+.win98-taskbar {
+  position: absolute;
+  left: 0;
+  right: 0;
+  bottom: 0;
+  height: 40px;
+  display: flex;
+  align-items: center;
+  gap: 6px;
+  padding: 4px;
+  background: #c0c0c0;
+  border-top: 2px solid #ffffff;
+  z-index: 40;
+}
+
+.win98-start {
+  display: inline-flex;
+  align-items: center;
+  gap: 6px;
+  height: 30px;
+  padding: 0 10px 0 8px;
+  font-weight: 700;
+}
+
+.win98-start__icon {
+  width: 16px;
+  height: 16px;
+  image-rendering: pixelated;
+}
+
+.win98-start__text {
+  line-height: 1;
+}
+
+.win98-taskbar__divider {
+  width: 2px;
+  height: 28px;
+  background: #808080;
+  box-shadow: 1px 0 0 #ffffff;
+}
+
+.win98-task {
+  height: 30px;
+  min-width: 160px;
+  max-width: 56vw;
+  padding: 0 10px;
+  font-weight: 400;
+  text-align: left;
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+}
+
+.win98-task {
+  /* Active window task button: depressed + dither fill (Win95-ish) */
+  background: var(--win98-dither) !important;
+  box-shadow: none !important;
+  border-top: 1px solid var(--win98-dkshadow) !important;
+  border-left: 1px solid var(--win98-dkshadow) !important;
+  border-right: 1px solid var(--win98-hi) !important;
+  border-bottom: 1px solid var(--win98-hi) !important;
+}
+
+.win98-start[aria-pressed="true"] {
+  /* Start button pressed: depressed + dither */
+  background: var(--win98-dither) !important;
+  box-shadow: none !important;
+  border-top: 1px solid var(--win98-dkshadow) !important;
+  border-left: 1px solid var(--win98-dkshadow) !important;
+  border-right: 1px solid var(--win98-hi) !important;
+  border-bottom: 1px solid var(--win98-hi) !important;
+}
+
+.win98-taskbar__spacer {
+  flex: 1;
+}
+
+.win98-tray {
+  display: inline-flex;
+  align-items: center;
+  height: 30px;
+  padding: 0 8px;
+  background: #c0c0c0;
+  border-top: 1px solid var(--win98-shadow);
+  border-left: 1px solid var(--win98-shadow);
+  border-right: 1px solid var(--win98-hi);
+  border-bottom: 1px solid var(--win98-hi);
+}
+
+.win98-tray__clock {
+  font-size: 11px;
+  color: #000000;
+  line-height: 1;
+  white-space: nowrap;
+}
+</style>