Bump G to D-Scripts to Debian 13 (Trixie)

[MickLesk]

✍️ Description

• Bump default container OS version from Debian 12 to 13 across multiple LXC setup scripts.
• Refactor update_script functions for consistency
• Improve messaging
• Standardize apt usage.
• Update Kimai install and update scripts to use setup_php, setup_composer, and fetch_and_deploy_gh_release helpers, and switch from MySQL to MariaDB.
• Update Kometa to use Python 3.13.
• Minor improvements to backup, cleanup, and service management steps in several scripts.

🔗 Related PR / Issue

Link: #

✅ 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.