feat(design): ok/warn/bad 语义色 token + btn-outline + 弹窗动效 keyframes

- tailwind 新增语义状态色三组(纸底文字级 600/700 对比度 ≥4.5:1,AA),
  色相降饱和贴近墨色印刷感;后续替换全部裸 tailwind 原色(emerald/amber/rose)
- 补 btn-outline 定义:此前三处使用但从未定义,样式静默失效
- 弹窗入场动画 keyframes:遮罩淡入 0.18s + 面板上浮 0.2s,仅 opacity/transform

frontend/src/index.css

@@ -103,6 +103,28 @@
   .btn-danger {
     @apply border-press bg-transparent text-press hover:bg-press hover:text-paper-50;
   }
+  /* 描边确认按钮:次级动作中需要比默认 btn 更明确轮廓的场合
+     (此前三处使用但从未定义,样式静默失效) */
+  .btn-outline {
+    @apply border-ink-900 bg-transparent text-ink-900
+           hover:border-press hover:bg-press-wash hover:text-press-dark;
+  }
+
+  /* ── 弹窗入场:遮罩淡入 + 面板上浮(仅 opacity/transform,GPU 友好) ── */
+  .modal-overlay-enter {
+    animation: modal-fade 0.18s ease-out both;
+  }
+  .modal-panel-enter {
+    animation: modal-rise 0.2s cubic-bezier(0.22, 1, 0.36, 1) both;
+  }
+  @keyframes modal-fade {
+    from { opacity: 0; }
+    to { opacity: 1; }
+  }
+  @keyframes modal-rise {
+    from { opacity: 0; transform: translateY(12px); }
+    to { opacity: 1; transform: translateY(0); }
+  }
 
   /* ── 统一空态 ── */
   .empty-state {