[FR] I hope to propose several improvements to the software, which include adding tagging and template functionalities, as well as optimizing the document export function

### Description

1. **Tagging Functionality**:
- Support for multi-level tags, enabling users to categorize documents in a hierarchical manner.
- The capability to create virtual collections or smart folders based on tags, automatically grouping all documents containing specific tags into a designated folder.

2. **Template Functionality**:
- The provision of document templates, allowing users to choose and apply pre-designed templates when creating new documents.

3. **Optimization of Document Export Feature**:
- Expand support for a wider array of document formats, such as docx, PDF, and others, thus enhancing compatibility and flexibility.
- Introduce a feature that enables the merging and exporting of multiple sub-documents: Upon selecting a top-level document, the software should have the ability to consolidate its nested or child documents into a single, continuous document during the export procedure.

### Impact

All users

### Additional Context

The above content was translated using a robot; please refer to the original text below for any errors.

### 希望能给软件增加标签功能、模板功能、优化文档导出功能。

**1、标签功能：**

- 支持多级标签；
- 能根据标签创建智能文档，将包含有指定标签的文档聚合到一个位置。

**2、模板功能：**

- 能创建文档模板，新建文档时可选择套用模板。

**3、优化文档导出功能：**

- 支持更多的文档格式，如：docx、PDF等等；
- 支持合并文档导出：当我选中某一级文档时，能将它的子文档合并导出到一个连续的文档。