feat: expose device-level autoconnect and managed controls

[ryux1]

Summary

• expose Device.autoconnect alongside the existing managed-state snapshot
• add high-level set_device_autoconnect and set_device_managed methods for any NetworkManager device
• cover both writes in the isolated veth lifecycle and document the new API

set_device_autoconnect(false) deliberately leaves an active connection alone, matching NetworkManager's property semantics. set_device_managed uses the writable property rather than the newer 1.58-only SetManaged method, preserving the crate's compatibility with older NetworkManager releases; its state is therefore temporary and resets when NetworkManager restarts.

Closes #541.

Validation

• cargo check
• cargo fmt --all -- --check
• cargo clippy --all-targets --all-features -- -D warnings
• cargo test -p nmrs --lib --all-features (647 passed)
• cargo test --doc --all-features --workspace (134 passed, 16 ignored)
• cargo test --all-features --workspace (647 unit tests and 134 doc tests passed; 5 environmental integration tests ignored)
• git diff --check

The Docker integration harness was not run locally because Docker is unavailable on this host. The updated ignored veth contract compiled as part of the workspace test and is ready for the repository's isolated CI environment.

AI assistance

I used OpenAI Codex to help inspect the existing API patterns, check the implementation, and draft parts of the code and documentation. I reviewed the complete diff and ran the validation listed above.

[ryux1]

The failing NetworkManager Integration job is in the pre-existing wifi_wpa_saved_connection_lifecycle test: NetworkManager returned DeviceFailed(Unknown) instead of the expected AuthFailed for a deliberately incorrect WPA passphrase. This PR only changes the wired lifecycle coverage, and the latest master CI run passed the same integration job. All other PR checks, including unit tests, Clippy, formatting, semver, aarch64, and docs, are green. I tried to rerun the failed job, but GitHub restricts reruns to repository admins; could a maintainer rerun it?

[cachebag]

Thanks, just need to tighten up this integration test. Great work!

[cachebag]

The failing NetworkManager Integration job is in the pre-existing wifi_wpa_saved_connection_lifecycle test: NetworkManager returned DeviceFailed(Unknown) instead of the expected AuthFailed for a deliberately incorrect WPA passphrase. This PR only changes the wired lifecycle coverage, and the latest master CI run passed the same integration job. All other PR checks, including unit tests, Clippy, formatting, semver, aarch64, and docs, are green. I tried to rerun the failed job, but GitHub restricts reruns to repository admins; could a maintainer rerun it?

@ryux1 I appreciate the work on this and LLMs are more than okay to use; but I don't need you to laundry the feedback I give through an LLM. I would like to speak to you as a human, since it is presumed that you take responsibility for your work regardless of how it was generated.

[cachebag]

LGTM

[ryux1]

Understood. Thanks for being direct, and thanks for reviewing and merging it.