improvement(wrapped): 清理主题系统，Wrapped 固定 Modern

- 移除 useWrappedTheme 与主题切换入口（仅保留 Modern 视觉）

- 封面/卡片/年份选择器/热力图等组件去掉 Win98/Gameboy/DOS 分支与样式

- 删除 themedHeatColor、CRT/像素字体相关样式，降低维护成本

frontend/utils/wrapped/heatmap.js

@@ -38,39 +38,6 @@ export const heatColor = (value, max) => {
   return `hsl(${hue.toFixed(1)} ${sat}% ${light.toFixed(1)}%)`
 }
 
-// Theme-aware heat color function
-export const themedHeatColor = (value, max, theme) => {
-  const v = Number(value) || 0
-  const m = Number(max) || 0
-  const t = (v > 0 && m > 0) ? clamp01(Math.sqrt(v / m)) : 0
-
-  switch (theme) {
-    case 'gameboy': {
-      // Game Boy 4-color palette: #0f380f, #306230, #8bac0f, #9bbc0f
-      if (t === 0) return '#9bbc0f'
-      if (t < 0.33) return '#8bac0f'
-      if (t < 0.66) return '#306230'
-      return '#0f380f'
-    }
-    case 'dos': {
-      // DOS green phosphor: from dark to bright green
-      if (t === 0) return 'rgba(51, 255, 51, 0.1)'
-      const light = 20 + 60 * t
-      return `hsl(120 100% ${light.toFixed(1)}%)`
-    }
-    case 'win98': {
-      // Win98-ish "system colors": gray -> blue highlight
-      if (t === 0) return '#dfdfdf'
-      if (t < 0.33) return '#c0c0c0'
-      if (t < 0.66) return '#808080'
-      return '#000080'
-    }
-    default:
-      // Modern (off) - use original heatColor
-      return heatColor(value, max)
-  }
-}
-
 export const formatHourRange = (hour) => {
   const h = Number(hour)
   if (!Number.isFinite(h)) return ''