refactor(admin): 接入 PasswordInput，删除分类改用 Modal 确认

- 登录弹窗与系统改密统一用 @stash/ui 的 PasswordInput（改密页补上显隐切换）
- 删除分类不再用 window.confirm，改用 Modal + 危险按钮（组件库推荐的组合）
- 删除页面私有的 PasswordInput 组件与 .password-field 样式

stash-web/src/components/admin/AdminPage.tsx

@@ -4,7 +4,9 @@ import {
   FormField,
   Icon,
   Input,
+  Modal,
   Notice,
+  PasswordInput,
   Select,
   Space,
   Switch,
@@ -55,6 +57,9 @@ export function AdminPage() {
   const [categories, setCategories] = useState<CategorySummary[]>([])
   const [tab, setTab] = useState('header')
   const [saving, setSaving] = useState(false)
+  /** 待删除的分类；非 null 时确认弹窗打开 */
+  const [pendingDelete, setPendingDelete] = useState<CategorySummary | null>(null)
+  const [deleting, setDeleting] = useState(false)
 
   const load = async () => {
     const [nextSession, nextDocument] = await Promise.all([fetchSession(), fetchSettings()])
@@ -94,14 +99,21 @@ export function AdminPage() {
     toast.success('已保存')
   }
 
-  const removeCategory = async (card: CategorySummary) => {
-    if (!window.confirm(`删除「${card.title}」会同时删除它下面的所有条目，确定继续？`)) return
-    const result = await deleteCategory(card.id)
+  const requestDelete = (card: CategorySummary) => setPendingDelete(card)
+
+  const confirmDelete = async () => {
+    if (pendingDelete === null) return
+    setDeleting(true)
+    const result = await deleteCategory(pendingDelete.id)
+    setDeleting(false)
+
     if (!result.ok) {
       toast.error(result.error)
       return
     }
-    toast.success(`已删除「${card.title}」`)
+
+    toast.success(`已删除「${pendingDelete.title}」`)
+    setPendingDelete(null)
     await load()
   }
 
@@ -179,7 +191,7 @@ export function AdminPage() {
                   categories={categories}
                   value={draft.sections}
                   onChange={(sections) => setDraft({ ...draft, sections })}
-                  onDelete={removeCategory}
+                  onDelete={requestDelete}
                   onReload={load}
                 />
               ) : tab === 'sidebar' ? (
@@ -187,7 +199,7 @@ export function AdminPage() {
                   categories={categories}
                   value={draft.sidebar}
                   onChange={(sidebar) => setDraft({ ...draft, sidebar })}
-                  onDelete={removeCategory}
+                  onDelete={requestDelete}
                   onReload={load}
                 />
               ) : tab === 'profile' ? (
@@ -228,6 +240,32 @@ export function AdminPage() {
           void load()
         }}
       />
+
+      <Modal
+        open={pendingDelete !== null}
+        onClose={() => {
+          if (!deleting) setPendingDelete(null)
+        }}
+        title={pendingDelete === null ? '删除分类' : `删除「${pendingDelete.title}」？`}
+        size="sm"
+        footer={
+          <Space gap="sm" justify="end">
+            <Button variant="secondary" disabled={deleting} onClick={() => setPendingDelete(null)}>
+              取消
+            </Button>
+            <Button
+              variant="danger"
+              loading={deleting}
+              icon={<Icon name="delete_2_line" />}
+              onClick={() => void confirmDelete()}
+            >
+              删除
+            </Button>
+          </Space>
+        }
+      >
+        <Text>删除后，该分类下的所有条目会一起删除，且不可恢复。</Text>
+      </Modal>
     </div>
   )
 }
@@ -663,17 +701,17 @@ function SystemPanel() {
   return (
     <Space direction="column" gap="lg" align="stretch" className="admin-form">
       <FormField label="当前密码" htmlFor="current-password">
-        <Input
+        <PasswordInput
           id="current-password"
-          type="password"
+          autoComplete="current-password"
           value={current}
           onChange={(event) => setCurrent(event.target.value)}
         />
       </FormField>
       <FormField label="新密码" htmlFor="next-password" hint="至少 8 位">
-        <Input
+        <PasswordInput
           id="next-password"
-          type="password"
+          autoComplete="new-password"
           value={next}
           onChange={(event) => setNext(event.target.value)}
         />