feat(admin): add book borrowing dialog and root redirect

- Add admin book borrowing dialog with user selection
- Add useAdminBorrowBook mutation with success/error toasts
- Fix sidebar z-index layering on admin layout
- Add RootRedirect component that routes based on admin role

src/components/layout/AdminLayout.tsx

@@ -31,7 +31,7 @@ export default function AdminLayout() {
   if (!isMobile) {
     return (
       <div className="flex min-h-screen">
-        <aside className="fixed top-0 left-0 flex h-full w-56 flex-col border-r bg-background">
+        <aside className="fixed top-0 left-0 z-50 flex h-full w-56 flex-col border-r bg-background">
           <div className="flex h-12 items-center gap-2 border-b px-4">
             <span className="font-heading text-base font-semibold">管理后台</span>
           </div>

src/features/admin/AdminBooksPage.tsx

@@ -17,7 +17,7 @@ import {
   AlertDialogHeader,
   AlertDialogTitle,
 } from "@/components/ui/alert-dialog"
-import { useAdminBooks, useAddBook, useUpdateBook, useUpdateStock, useDeleteBook } from "./hooks"
+import { useAdminBooks, useAddBook, useUpdateBook, useUpdateStock, useDeleteBook, useAdminBorrowBook } from "./hooks"
 import { usePlatform } from "@/hooks/usePlatform"
 import { useIsMobile } from "@/hooks/useIsMobile"
 import type { Book } from "@/types/api"
@@ -27,6 +27,7 @@ interface AddDialog { open: boolean }
 interface EditDialog { open: boolean; book: Book }
 interface StockDialog { open: boolean; book: Book }
 type DeleteDialog = { open: boolean; book: Book } | { open: false; book: null }
+interface BorrowDialog { open: boolean; book: Book }
 
 const addInitial: AddDialog = { open: false }
 
@@ -40,6 +41,7 @@ export default function AdminBooksPage() {
   const [edit, setEdit] = useState<EditDialog | null>(null)
   const [stock, setStock] = useState<StockDialog | null>(null)
   const [del, setDel] = useState<DeleteDialog>({ open: false, book: null })
+  const [borrow, setBorrow] = useState<BorrowDialog | null>(null)
 
   if (isLoading) return <AdminBooksSkeleton isMobile={isMobile} />
   if (error) {
@@ -93,6 +95,9 @@ export default function AdminBooksPage() {
                     <Button size="xs" variant="destructive" onClick={() => setDel({ open: true, book: b })}>
                       删除
                     </Button>
+                    <Button size="xs" variant="outline" disabled={b.stock <= 0} onClick={() => setBorrow({ open: true, book: b })}>
+                      手动借阅
+                    </Button>
                   </div>
                 </TableCell>
               </TableRow>
@@ -120,6 +125,9 @@ export default function AdminBooksPage() {
                   <Button size="xs" variant="destructive" onClick={() => setDel({ open: true, book: b })}>
                     删除
                   </Button>
+                  <Button size="xs" variant="outline" disabled={b.stock <= 0} onClick={() => setBorrow({ open: true, book: b })}>
+                    手动借阅
+                  </Button>
                 </div>
               </CardContent>
             </Card>
@@ -133,6 +141,7 @@ export default function AdminBooksPage() {
       {del.book && (
         <DeleteBookDialog book={del.book} open onClose={() => setDel({ open: false, book: null })} />
       )}
+      {borrow && <BorrowDialog_ book={borrow.book} open onClose={() => setBorrow(null)} />}
     </div>
   )
 }
@@ -302,6 +311,45 @@ function DeleteBookDialog({ book, open, onClose }: { book: Book; open: boolean;
   )
 }
 
+// ---- Manual Borrow Dialog ----
+function BorrowDialog_({ book, open, onClose }: { book: Book; open: boolean; onClose: () => void }) {
+  const mutation = useAdminBorrowBook()
+  const [userId, setUserId] = useState("")
+
+  useEffect(() => {
+    if (!open) setUserId("")
+  }, [open])
+
+  async function submit(e: FormEvent) {
+    e.preventDefault()
+    if (!userId.trim()) return
+    await mutation.mutateAsync({ bookId: book.id!, userId: Number(userId) })
+    onClose()
+  }
+
+  return (
+    <Dialog open={open} onOpenChange={(o) => !o && onClose()}>
+      <DialogContent>
+        <DialogHeader>
+          <DialogTitle>手动借阅 — {book.name}</DialogTitle>
+        </DialogHeader>
+        <form onSubmit={submit} className="space-y-4">
+          <div className="space-y-2">
+            <Label htmlFor="borrow-userid">用户 ID</Label>
+            <Input id="borrow-userid" type="number" min={1} required value={userId} onChange={(e) => setUserId(e.target.value)} placeholder="输入用户 ID" />
+          </div>
+          <DialogFooter>
+            <Button type="submit" disabled={mutation.isPending}>
+              {mutation.isPending && <Loader2Icon className="animate-spin" />}
+              确认借阅
+            </Button>
+          </DialogFooter>
+        </form>
+      </DialogContent>
+    </Dialog>
+  )
+}
+
 // ---- Skeleton ----
 function AdminBooksSkeleton({ isMobile }: { isMobile: boolean }) {
   if (isMobile) {

src/features/admin/hooks.ts

@@ -2,7 +2,7 @@ import { useQuery, useMutation, useQueryClient } from "@tanstack/react-query"
 import { toast } from "sonner"
 import { getAllBooks } from "@/api/books"
 import { addBook, deleteBook, updateBook, updateStock } from "@/api/admin/books"
-import { getAllBorrows, searchBorrows, returnBook } from "@/api/admin/borrows"
+import { getAllBorrows, searchBorrows, returnBook, borrowBook as adminBorrowBook } from "@/api/admin/borrows"
 
 export function useAdminBooks() {
   return useQuery({
@@ -96,3 +96,18 @@ export function useAdminReturnBook() {
     },
   })
 }
+
+export function useAdminBorrowBook() {
+  const qc = useQueryClient()
+  return useMutation({
+    mutationFn: ({ bookId, userId }: { bookId: number; userId: number }) =>
+      adminBorrowBook(bookId, userId),
+    onSuccess: () => {
+      qc.invalidateQueries({ queryKey: ["admin", "borrows"] })
+      toast.success("借阅成功")
+    },
+    onError: (err) => {
+      toast.error(err instanceof Error ? err.message : "借阅失败")
+    },
+  })
+}

src/router/index.tsx

@@ -1,5 +1,6 @@
 import { createBrowserRouter, Navigate } from "react-router-dom"
 import { ProtectedRoute, AdminRoute } from "./guards"
+import { useAuthStore } from "@/store/authStore"
 import LoginPage from "@/features/auth/LoginPage"
 import BooksPage from "@/features/books/BooksPage"
 import MyBorrowsPage from "@/features/borrows/MyBorrowsPage"
@@ -8,6 +9,11 @@ import AdminBorrowsPage from "@/features/admin/AdminBorrowsPage"
 import AppLayout from "@/components/layout/AppLayout"
 import AdminLayout from "@/components/layout/AdminLayout"
 
+function RootRedirect() {
+  const isAdmin = useAuthStore((s) => s.isAdmin())
+  return <Navigate to={isAdmin ? "/admin/books" : "/books"} replace />
+}
+
 export const router = createBrowserRouter([
   {
     path: "/login",
@@ -18,7 +24,7 @@ export const router = createBrowserRouter([
     children: [
       {
         path: "/",
-        element: <Navigate to="/books" replace />,
+        element: <RootRedirect />,
       },
       {
         path: "/books",