feat(export-to-word): add S3 object storage support

- Add boto3 direct download for S3/MinIO stored images
- Implement 6-level file fallback: DB → S3 → Local → URL → API → Attributes
- Sync S3 support to Chinese version (export_to_word_cn.py)
- Update version to 0.4.2
- Rewrite README.md and README_CN.md following standard format
- Update docs version numbers
- Add file storage access guidelines to copilot-instructions.md

docs/plugins/actions/export-to-word.md

@@ -1,7 +1,7 @@
 # Export to Word
 
 <span class="category-badge action">Action</span>
-<span class="version-badge">v0.4.1</span>
+<span class="version-badge">v0.4.2</span>
 
 Export conversation to Word (.docx) with **syntax highlighting**, **native math equations**, **Mermaid diagrams**, **citations**, and **enhanced table formatting**.
 

docs/plugins/actions/export-to-word.zh.md

@@ -1,7 +1,7 @@
 # Export to Word（导出为 Word）
 
 <span class="category-badge action">Action</span>
-<span class="version-badge">v0.4.1</span>
+<span class="version-badge">v0.4.2</span>
 
 将当前对话导出为完美格式的 Word 文档，支持**代码语法高亮**、**原生数学公式**、**Mermaid 图表**、**引用资料**以及**增强表格**渲染。
 

docs/plugins/actions/index.md

@@ -63,7 +63,7 @@ Actions are interactive plugins that:
 
     Export the current conversation to a formatted Word doc with **syntax highlighting**, **native math equations**, **Mermaid diagrams**, **citations**, and **enhanced table formatting**.
     
-    **Version:** 0.4.1
+    **Version:** 0.4.2
 
     [:octicons-arrow-right-24: Documentation](export-to-word.md)
 

docs/plugins/actions/index.zh.md

@@ -63,7 +63,7 @@ Actions 是交互式插件，能够：
 
     将当前对话导出为完美格式的 Word 文档，支持**代码语法高亮**、**原生数学公式**、**Mermaid 图表**、**引用资料**以及**增强表格**渲染。
 
-    **版本：** 0.4.1
+    **版本：** 0.4.2
 
     [:octicons-arrow-right-24: 查看文档](export-to-word.md)