fix(ui): 深色模式下补齐卡片与弹层的层次感

- 深色里沿用浅色那套低透明度黑色阴影没有对比度（黑投影落在 zinc-950 上），
  悬停和弹层都看不出「浮起来」，本次为深色单独配一套阴影与状态色
- 卡片：静止态改「近距投影 + 顶部内高光」；悬停改「外扩暗晕 + 极淡白光晕 +
  内高光 12%」，同时底色提亮一档（zinc-900 → zinc-800）、边框提到 zinc-600，
  位移补偿到 2px —— 暗底上 1px 的移动肉眼看不出来
- 弹层：新增 shadow-pop-dark / shadow-panel-dark 标记类，只挂给深色底面的
  下拉与抽屉；toast 在深色下仍是亮色块（dark:bg-zinc-100），保留原黑色投影，
  避免亮块套白光晕发脏
- 抽屉补 dark:border-l：它在深色下既无边框又无可视阴影，与背景糊成一片
- 实现说明：Tailwind v4 会把 @theme 的阴影值内联进 --tw-shadow，覆盖 CSS 变量
  对已生成的工具类无效，因此直接重写 box-shadow；规则不放进 @layer 以便稳定
  压过原子类，且选择器需按 hover: 变体转义后的类名书写

验证：vue-tsc -b 与 eslint src 干净；TaskCard / SideDrawer / TagFilter /
TagInput / BatchSelectionBar 共 114 例单测通过；另用 Playwright 采样像素亮度
与 getComputedStyle 确认深浅两套阴影各自命中。

src/components/BatchSelectionBar.vue

@@ -236,7 +236,7 @@ function onDueChange(value: string | null): void {
 
           <div
             v-if="dueOpen"
-            class="absolute top-full left-0 z-30 mt-1.5 w-56 rounded-lg border border-slate-200 bg-white p-2 shadow-pop dark:border-zinc-700 dark:bg-zinc-900"
+            class="absolute top-full left-0 z-30 mt-1.5 w-56 rounded-lg border border-slate-200 bg-white p-2 shadow-pop shadow-pop-dark dark:border-zinc-700 dark:bg-zinc-900"
           >
             <DatePicker
               :model-value="batchDue"

src/components/SideDrawer.vue

@@ -108,7 +108,7 @@ onBeforeUnmount(stopListening)
 
       <aside
         ref="panelRef"
-        class="absolute inset-y-0 right-0 flex w-full max-w-md flex-col bg-white shadow-panel outline-none dark:bg-zinc-900"
+        class="absolute inset-y-0 right-0 flex w-full max-w-md flex-col bg-white shadow-panel shadow-panel-dark outline-none dark:border-l dark:border-zinc-800 dark:bg-zinc-900"
         role="dialog"
         aria-modal="true"
         :aria-label="title"

src/components/TagFilter.vue

@@ -86,7 +86,7 @@ onBeforeUnmount(() => {
 
     <div
       v-if="open"
-      class="absolute top-full left-0 z-20 mt-1.5 w-56 rounded-lg border border-slate-200 bg-white p-1.5 shadow-pop dark:border-zinc-700 dark:bg-zinc-900"
+      class="absolute top-full left-0 z-20 mt-1.5 w-56 rounded-lg border border-slate-200 bg-white p-1.5 shadow-pop shadow-pop-dark dark:border-zinc-700 dark:bg-zinc-900"
     >
       <p v-if="tags.length === 0" class="px-2 py-3 text-center text-xs text-slate-400 dark:text-zinc-500">
         还没有任何标签

src/components/TagInput.vue

@@ -169,7 +169,7 @@ function onBlur(): void {
       id="tag-suggestions"
       role="listbox"
       aria-label="已有标签"
-      class="absolute top-full left-0 z-20 mt-1 max-h-44 w-full overflow-y-auto rounded-lg border border-slate-200 bg-white p-1 shadow-pop dark:border-zinc-700 dark:bg-zinc-900"
+      class="absolute top-full left-0 z-20 mt-1 max-h-44 w-full overflow-y-auto rounded-lg border border-slate-200 bg-white p-1 shadow-pop shadow-pop-dark dark:border-zinc-700 dark:bg-zinc-900"
     >
       <li
         v-for="(tag, index) in candidates"

src/components/TaskCard.vue

@@ -98,7 +98,7 @@ const cardClass = computed(() => {
   }
   return isDone.value
     ? 'border-slate-200 bg-white opacity-60 dark:border-zinc-800 dark:bg-zinc-900'
-    : 'border-slate-200 bg-white hover:-translate-y-px hover:border-slate-300 hover:shadow-card-hover dark:border-zinc-800 dark:bg-zinc-900 dark:hover:border-zinc-700'
+    : 'border-slate-200 bg-white hover:-translate-y-px hover:border-slate-300 hover:shadow-card-hover dark:border-zinc-800 dark:bg-zinc-900 dark:hover:border-zinc-600 dark:hover:bg-zinc-800'
 })
 
 /**