Include field library metadata in template exports

- Add fieldLibrary metadata to HTML template packages, including form fields, custom time formats, multi-select options, and anesthesia options.

- Restore imported template field metadata into local compatibility caches and the backend field library API when available.

- Preserve legacy JSON template import compatibility while keeping user-facing exports on HTML packages.

- Prevent template field saves from overwriting stored multi-select and anesthesia options with empty values.

- Update README, AGENTS, feature, requirement, design, module, progress, component, and testing docs for complete template export behavior.

- Extend template export tests to cover field library metadata round-tripping.

docs/modules/template-management.md

@@ -76,15 +76,21 @@
 
 ```json
 {
-  "version": "1.0",
+  "version": "1.1",
   "type": "surclaw_template_package",
   "title": "模板名称",
   "description": "模板描述",
   "content": "模板 HTML",
-  "fields": []
+  "fields": [],
+  "fieldLibrary": {
+    "formFields": [],
+    "customTimeFormats": [],
+    "multiSelectOptions": {},
+    "anesthesiaOptions": []
+  }
 }
 ```
 
-HTML 模板包是一个可直接用浏览器打开的完整 HTML 文件，包含 A4 页面样式、打印样式和内嵌的 `surclaw_template_package` 元数据。它比 JSON 更适合保留“报告整体观感”，也是当前推荐的可回导模板交换格式。
+HTML 模板包是一个可直接用浏览器打开的完整 HTML 文件，包含 A4 页面样式、打印样式和内嵌的 `surclaw_template_package` 元数据。元数据会随包保存模板正文、模板对应字段，以及字段管理相关设置：字段库、时间格式、多选字段选项和麻醉方式选项。它比单独 JSON 文件更适合保留“报告整体观感”，也是当前推荐的可回导模板交换格式。
 
 PDF 导出走浏览器打印，适合归档和人工查看，不适合再次导入编辑。