monitor-all: improvements - tag based filtering

[grizmin]

✍️ Description

🧩 1. Tag-Based Filtering (Core Feature)
New feature: Only restart instances (VMs or containers) that have the mon-restart tag.

This makes monitoring and auto-restart controllable directly from the Proxmox Web UI, without editing scripts or services.

Set via GUI: VM → Options → Tags → mon-restart

Set via CLI: qm set -tags mon-restart or pct set -tags mon-restart

This is the primary new control mechanism, making the script safer, more flexible, and user-friendly.

🧰 2. Backward-Compatible Exclusion Mechanism
The original feature that lets you exclude instances via CLI arguments is preserved:

./ping-instances.sh 101 300
These IDs will always be skipped regardless of tag.

🧠 3. Intelligent Responsiveness Checks
For VMs:

Uses qm guest cmd ping to check responsiveness via the QEMU guest agent.

No longer relies on network-level ping, which can be misleading or blocked.

For containers (CTs):

Uses traditional ping to IP addresses obtained from pct exec, since CTs don’t support QEMU agent.

⛔ 4. Instance Skipping Improvements
Instances are now skipped if:

They are explicitly excluded via CLI.

They are templates.

They are configured with onboot: 0 or missing.

They lack the mon-restart tag, regardless of other status.

🪵 5. Same Logging Behavior
All output continues to go to /var/log/ping-instances.log for persistent tracking.

Verbose messages were added for traceability (e.g., why a VM or CT was skipped).

🎯 Why This Matters
With tag-based control, admins can now manage restart behavior dynamically from the Proxmox Web UI, making the script:

More secure (no accidental restarts).

More maintainable (no script edits needed).

More user-friendly (integrated with the UI workflow).

🔗 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.