前端: 浅色模式 + 系统自动主题

- 引入语义化 CSS 变量令牌(bg/surface/edge/ink/muted/accent 等), data-theme 三态切换
- theme store(localStorage + 系统偏好跟随), 首屏内联脚本防主题闪烁
- ThemeToggle 组件(浅色/深色/跟随系统) 置于导航与控制台顶栏
- 全量替换硬编码 zinc/emerald/red 类为令牌, 图表基线/状态色随主题适配
- 浅色对比度校准(accent/err/warn 深浅各一套)

Co-Authored-By: Claude <noreply@anthropic.com>

web/src/components/ui/Button.vue

@@ -16,9 +16,9 @@ withDefaults(
     class="inline-flex items-center justify-center gap-2 rounded-md font-medium transition-[transform,background-color,border-color,color] duration-150 active:scale-[0.98] disabled:pointer-events-none disabled:opacity-50 select-none"
     :class="[
       size === 'sm' ? 'h-8 px-3 text-xs' : 'h-10 px-4 text-sm',
-      variant === 'primary' && 'bg-accent text-zinc-950 hover:bg-accent-strong',
-      variant === 'ghost' && 'border border-zinc-700 text-zinc-200 hover:border-zinc-500 hover:bg-zinc-800/60',
-      variant === 'danger' && 'border border-err/50 text-red-300 hover:border-err hover:bg-err/10',
+      variant === 'primary' && 'bg-accent text-accent-ink hover:bg-accent-strong',
+      variant === 'ghost' && 'border border-edge2 text-ink hover:border-edge2 hover:bg-surface2/60',
+      variant === 'danger' && 'border border-err/50 text-err hover:border-err hover:bg-err/10',
     ]"
   >
     <span v-if="loading" class="size-3.5 animate-spin rounded-full border-2 border-current border-t-transparent" />