feat: add dsl backup plugin

[leslie2046]

Plugin Submission Form

1. Metadata

• Plugin Author: leslie2046
• Plugin Name: dify_backup_plugin
• Repository URL: https://github.com/leslie2046/dify_backup_plugin

2. Submission Type

• New plugin submission
• Version update for existing plugin

3. Description

• Export All Apps
  Batch export DSL configurations for all applications in the workspace.
• Export Single App
  Export DSL configuration for a specific application.
• Export All app's annotations.

4. Checklist

• I have read and followed the Publish to Dify Marketplace guidelines
• I have read and comply with the Plugin Developer Agreement
• I confirm my plugin works properly on both Dify Community Edition and Cloud Version
• I confirm my plugin has been thoroughly tested for completeness and functionality
• My plugin brings new value to Dify

5. Documentation Checklist

Please confirm that your plugin README includes all necessary information:

• Step-by-step setup instructions
• Detailed usage instructions
• All required APIs and credentials are clearly listed
• Connection requirements and configuration details
• Link to the repository for the plugin source code

6. Privacy Protection Information

Based on Dify Plugin Privacy Protection Guidelines:

Data Collection

Privacy Policy

• I confirm that I have prepared and included a privacy policy in my plugin package based on the Plugin Privacy Protection Guidelines

[crazywoola]

✅ LGTM

Decision: Approve

Local Check Results

Check	Status	Detail
Manifest author	✅ Pass	author is valid.
Icon validation	✅ Pass	icon exists: _assets/icon.svg
Version check	✅ Pass	version 0.0.3 is available.
README language	✅ Pass	README.md CJK ratio=0.0% (zh=0, en=2430, allowed_zh<=0)
Dependency install	✅ Pass	requirements installed successfully.
Install test	✅ Pass	plugin install test passed.
Packaging test	✅ Pass	packaging check passed.