fix(frontend): 补充 book_id 输入可访问名称

为番茄 book_id 输入框补充可访问名称，避免辅助技术无法命中该输入。
补充对应回归测试，防止后续重构再次丢失该可访问性语义。

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: papysans

frontend/src/pages/ChapterWorkbenchPage.tsx

@@ -1330,6 +1330,7 @@ export default function ChapterWorkbenchPage() {
                                 <input
                                     type="text"
                                     className="input"
+                                    aria-label="番茄 book_id"
                                     style={{ width: 120, fontSize: '0.78rem', padding: '2px 6px' }}
                                     value={fanqieBookIdInput}
                                     placeholder="未绑定"

frontend/src/pages/__tests__/ChapterWorkbenchPage.test.tsx

@@ -339,6 +339,15 @@ describe('ChapterWorkbenchPage', () => {
         })
     })
 
+    it('book_id 输入框提供可访问名称', async () => {
+        renderPage()
+        await waitFor(() => {
+            expect(screen.getByText('book_id：')).toBeTruthy()
+        })
+
+        expect(screen.getByLabelText('番茄 book_id')).toBeTruthy()
+    })
+
     it('book_id 输入框会在用户编辑后仍跟随项目 store 刷新后的值更新', async () => {
         const view = renderPage()
         await waitFor(() => {