feat: add Cloud Clipboard app

[wm88990]

Summary

Add Cloud Clipboard (TransparentLC/cloud-clipboard) to the Docker App Store.

Cloud Clipboard is a self-hosted online clipboard tool that supports text and file transfer between devices, running on port 9501.

What's included

File	Description
apps/cloud-clipboard/app.json	App configuration (appid=301, type=Tools)
apps/cloud-clipboard/ico-dkapp_cloud-clipboard.png	100x100 app icon
apps/cloud-clipboard/cloud-clipboard/docker-compose.yml	Docker Compose template
apps/cloud-clipboard/cloud-clipboard/.env	Environment variables

App details

• Image: jonnyan404/cloud-clipboard:latest
• Port: 9501
• Type: Tools
• Depends on: None
• Custom settings:
  • CLIP_NO_AUTH: Toggle password-free access
  • CLIP_HISTORY: Clipboard history limit (default: 100)
  • CLIP_TEXT_SIZE: Text size limit (default: 8192 chars)
  • CLIP_FILE_SIZE: File size limit (default: 10240 MB)
  • CLIP_EXPIRE_TIME: Expiration time (default: 24h)

Checklist

• app.json with all required fields
• ico-dkapp_cloud-clipboard.png (100x100 PNG)
• docker-compose.yml with labels.createdBy: bt_apps
• .env with HOST_IP, CPUS, MEMORY_LIMIT, APP_PATH
• No database dependencies
• Passed local validation script