Run cEOS postdeploy through container runtime

[orrious]

No description provided.

[ankudinov]

@orrious Not sure what is this PR about but as it's not in a draft status - please add the docs and tests required before making it ready for review.

[orrious]

Addressed the requested follow-up on this PR.

Changes pushed:

• added cEOS postdeploy unit tests
• added cEOS coverage for runtime-assigned Management0 IPv4 in Robot
• added the corresponding docs note
• fixed the unit test endpoint type issue

Validation:

• real x86 runner: go test ./nodes/ceos and build passed
• real ARM runner: go test ./nodes/ceos and build passed
• GitHub-hosted build/unit/docs jobs also passed on amd64 and arm64; hosted cEOS integration failed only on GHCR image pull

[orrious]

@ankudinov Following up on your July 28 review: the requested docs and tests are now added on this branch, along with the cEOS Robot coverage described in the latest update. Please take another look when you have a moment.