Kernel-Clean: detect meta-packages and fix silent removal failures

[MickLesk]

✍️ Description

• Replace grep 'kernel-.*-pve' with an awk /^ii/ + grep -E '^proxmox-kernel-[0-9]+.[0-9]+.[0-9]' pipeline. This filters out rc-state (config-only) packages and the two-segment meta-packages (proxmox-kernel-X.Y) that the old regex missed entirely.

• for each selected kernel, the script now derives the corresponding meta-package name (proxmox-kernel-X.Y) and co-purges it when no other versioned kernel of that minor version remains installed. This prevents apt from blocking or undoing the removal due to the reverse dependency the meta-package holds.

🔗 Related Issue

Fixes #14661

✅ 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.

---

🛠️ 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 script metadata (PocketBase/website data).
• 🔧 Refactoring / Code Cleanup – Improves readability or maintainability without changing functionality.
• 📝 Documentation update – Changes to README, AppName.md, CONTRIBUTING.md, or other docs.