feat(test-guest): add snap lifecycle reproduction harness

[elezar]

Summary

Add a reusable Ubuntu Snap lifecycle harness for reproducing package install and interface-connection failures in a disposable local VM.

Related Issue

Related to #2055. This PR provides the reproduction and validation harness; it does not change packaged gateway behavior.

Changes

• Add an Ubuntu snapd guest configuration.
• Add --copy-file for Snap artifacts and other non-executable guest files.
• Add a repeatable Snap install/connect/status scenario with diagnostics and optional bounded recovery checking.
• Document the local workflow.

Testing

• mise run pre-commit passes
• nix run .#test-guest -- --list
• Local ARM64 Ubuntu guest reproduction against the Release Dev Snap artifact
• Unit tests added/updated
• E2E tests added/updated (if applicable)

Checklist

• Follows Conventional Commits
• Commits are signed off (DCO)

[copy-pr-bot]

Auto-sync is disabled for draft pull requests in this repository. Workflows must be run manually.

Contributors can view more details about this message here.