improvement(wrapped-ui): 移除 VHS 主题并优化 DOS/CRT 视觉效果

- 主题系统收敛为 Modern/Game Boy/DOS（快捷键改为 F1-F3）
- 删除 VHS 切换器与相关样式（卡片/控件/年份选择/图表等）
- DOS 主题统一使用像素字体，减弱发光强度并细化扫描线/闪烁参数
- DOS 闪烁光标改由 WrappedCRTOverlay 渲染，避免全局样式副作用
- 移除热力图 vhs 配色分支

frontend/components/wrapped/visualizations/GlobalOverviewChart.vue

@@ -377,56 +377,4 @@ const labels = computed(() => {
   color: #33ff33 !important;
   text-shadow: 0 0 5px #33ff33;
 }
-
-/* ========== VHS 主题 ========== */
-
-.wrapped-theme-vhs .overview-card {
-  background: #16213e !important;
-  border: 1px solid #0f3460 !important;
-  backdrop-filter: none;
-}
-
-.wrapped-theme-vhs .overview-grid-line {
-  stroke: #0f3460;
-  stroke-opacity: 0.6;
-}
-
-.wrapped-theme-vhs .overview-axis-line {
-  stroke: #0f3460;
-  stroke-opacity: 0.8;
-}
-
-.wrapped-theme-vhs .overview-data-polygon {
-  fill: rgba(233, 69, 96, 0.2);
-  stroke: #e94560;
-}
-
-.wrapped-theme-vhs .overview-data-node {
-  fill: #e94560;
-  stroke: #16213e;
-}
-
-.wrapped-theme-vhs .overview-label {
-  fill: #a0a0a0;
-}
-
-.wrapped-theme-vhs .overview-progress-bg {
-  background: #0f3460 !important;
-}
-
-.wrapped-theme-vhs .overview-progress-fill {
-  background: linear-gradient(90deg, #e94560, #0f3460) !important;
-}
-
-.wrapped-theme-vhs .wrapped-label,
-.wrapped-theme-vhs .wrapped-body {
-  color: #a0a0a0 !important;
-}
-
-.wrapped-theme-vhs .wrapped-number {
-  color: #e94560 !important;
-  text-shadow:
-    -1px 0 rgba(0, 255, 247, 0.5),
-    1px 0 rgba(255, 0, 255, 0.5);
-}
 </style>