chore: 新增\更新分片内容，长度限制1200以内

src/views/personal-space/personal-knowledge/components/add-knowledge-chunk-modal.vue

@@ -95,6 +95,8 @@ function handleConfirm() {
             type="textarea"
             :placeholder="t('personal_space_module.knowledge_module.knowledge_chunk_content_input_placeholder')"
             :rows="23"
+            :maxlength="1200"
+            show-count
           />
         </n-form-item>
       </n-form>

src/views/personal-space/personal-knowledge/components/edit-knowledge-chunk-modal.vue

@@ -108,6 +108,8 @@ function handleConfirm() {
             type="textarea"
             :placeholder="t('personal_space_module.knowledge_module.knowledge_chunk_content_input_placeholder')"
             :rows="23"
+            :maxlength="1200"
+            show-count
           />
         </n-form-item>
       </n-form>