fix: 修复图书类型不匹配问题 - 将 '普通图书' 改为 '实体书' 以匹配 BookFactoryProvider 支持的类型

backend/src/main/resources/templates/add-book.html

@@ -24,7 +24,7 @@
                             <div class="mb-3">
                                 <label for="bookType" class="form-label">图书类型</label>
                                 <select class="form-select" id="bookType" name="bookType" required>
-                                    <option value="普通图书">普通图书</option>
+                                    <option value="实体书">实体书</option>
                                     <option value="电子书">电子书</option>
                                     <option value="期刊">期刊</option>
                                 </select>

backend/src/test/java/com/smartlibrary/backend/controller/WebControllerTest.java

@@ -99,7 +99,7 @@ class WebControllerTest {
     @Test
     void testAddBookSuccess() throws Exception {
         mockMvc.perform(post("/books/add")
-                        .param("bookType", "普通图书")
+                        .param("bookType", "实体书")
                         .param("title", "测试图书")
                         .param("author", "测试作者")
                         .param("isbn", "978-1234567890")
@@ -113,7 +113,7 @@ class WebControllerTest {
     @Test
     void testAddBookInvalidDate() throws Exception {
         mockMvc.perform(post("/books/add")
-                        .param("bookType", "普通图书")
+                        .param("bookType", "实体书")
                         .param("title", "测试图书")
                         .param("author", "测试作者")
                         .param("isbn", "978-0000000000")