Expand reboot command environment placeholders

[msander]

Summary

• move the shared base environment builder onto the config so it can be reused outside the CLI helpers
• expand reboot command arguments with the injected environment before logging/executing and cover the behaviour with tests
• refresh operations/state docs to point at the new environment source and mention the expanded command context

Testing

• go test ./...

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https://chatgpt.com/codex/tasks/task_b_68cdc16fbeac8321801a6a4d29d8ae95