[MickLesk]

✍️ Description

Staging moved from /tmp to disk in #218, and the deploy step still copied the unpacked release into its target, so it was on disk twice. LibreNMS on its 4 GB disk ran out of space in 41 installs within four days. The tarball mode ignored cp's failure and returned 0, so the install went on with a partial tree and only failed when it could not write the version file.

Entries the target does not have yet are now moved, the rest copied over and removed from staging. A failed deploy on a full disk says so and returns 252.

🔗 Related Issue

Fixes #

✅ Prerequisites (X in brackets)

• Self-review completed – Code follows project standards.
• Tested thoroughly – Changes work as expected (Proxmox VE and/or Incus, as applicable).
• No security risks – No hardcoded secrets, unnecessary privilege escalations, or permission issues.
• API.txt regenerated – If a function signature or behavior changed, API.txt was updated to match.

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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 behavior in a way that may require updates in every downstream script.
• 🔧 Refactoring / Code Cleanup – Improves readability or maintainability without changing functionality.
• 📝 Documentation update – Changes to README, docs/, CONTRIBUTING.md, or other docs.

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Select exactly one option.

• No AI used – Code was written without AI assistance.
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