修复: 前端UI审查问题(项目状态badge+confirm替换+加载态+CSS修正)

- ProjectDetail: 加载态/不存在态 + stage badge CSS 类名修正(7个实际状态)

- Tasks: confirm()替换为useConfirm + 死代码清理 + priority CSS去重

- Knowledge: 列表加载态

- Projects: CSS变量名拼写修正(--df-mono→--df-font-mono)

- EmptyState: opacity从容器移到图标(对比度修复)

- Ideas: 5处内联style替换为modal-field class

- ProjectDetail: 删除注释stages死代码

src/components/ai/EmptyState.vue

@@ -72,9 +72,8 @@ const examplePrompts = [
   align-items: center;
   justify-content: center;
   gap: 8px;
-  opacity: 0.5;
 }
-.ai-empty-icon { margin-bottom: 4px; }
+.ai-empty-icon { margin-bottom: 4px; opacity: 0.4; }
 .ai-empty-text {
   font-size: 14px;
   font-weight: 500;