Install rsync in ct/commafeed.sh

[mzhaodev]

✍️ Description

This PR installs rsync in the update script of commafeed for users who used the install script before rsync was added. This prevents users from seeing a command not found error when attempting to upgrade commafeed.

🔗 Related PR / Issue

✅ Prerequisites (X in brackets)

• Self-review completed – Code follows project standards.
• Tested thoroughly – Changes work as expected.
• No security risks – No hardcoded secrets, unnecessary privilege escalations, or permission issues.

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🛠️ Type of Change (X in brackets)

• 🐞 Bug fix – Resolves an issue without breaking functionality.
• ✨ New feature – Adds new, non-breaking functionality.
• 💥 Breaking change – Alters existing functionality in a way that may require updates.
• 🆕 New script – A fully functional and tested script or script set.
• 🌍 Website update – Changes to website-related JSON files or metadata.
• 🔧 Refactoring / Code Cleanup – Improves readability or maintainability without changing functionality.
• 📝 Documentation update – Changes to README, AppName.md, CONTRIBUTING.md, or other docs.

[tremor021]

You should check if rsync is installed and install if needed only. The way you have it, it will always try to install it, use this instead:

if ! [[ $(dpkg -s rsync 2>/dev/null) ]]; then
    $STD apt-get update
    $STD apt-get install -y rsync
  fi

[mzhaodev]

My understanding is that apt-get would only install rsync if it is out-of-date, in which case I don't think it's terrible to upgrade it. Regardless, I have added the check.