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/views/Projects.vue

@@ -579,7 +579,7 @@ async function runImport() {
 .import-table tbody td { padding: 8px 10px; border-bottom: 0.5px solid var(--df-border); vertical-align: top; color: var(--df-text-secondary); }
 .import-table tbody tr:last-child td { border-bottom: none; }
 .import-table .col-check { width: 32px; text-align: center; }
-.import-table .col-path { max-width: 260px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; font-family: var(--df-mono, monospace); font-size: 11px; }
+.import-table .col-path { max-width: 260px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; font-family: var(--df-font-mono, monospace); font-size: 11px; }
 .row-disabled { opacity: 0.5; }
 .imp-name { font-weight: 500; color: var(--df-text); }
 .mono-tag { margin-left: 6px; font-size: 10px; padding: 1px 6px; border-radius: var(--df-radius-xs); background: rgba(255,217,61,0.15); color: var(--df-warning); border: 0.5px solid var(--df-border); }