fix(validate): return correct node_id for nodes without a label

[bhuvan-somisetty]

Fixes #592

The node id was sliced out of the warning with a fixed -9, but has no label is 13 chars, so JSON output gave "n1 has" instead of "n1". Now slices by the actual suffix length.

Added a test that checks node_id and nodes_affected for an unlabeled node.

[bhuvan-somisetty]

@pradeeban thanks for reviewing and merging the last few PRs, really appreciate it.

I've mostly been picking up smaller bugs in the CLI and the Python runtime so far. Is there any area you'd like me to focus on more going forward? Could be a part of the codebase that needs more attention, or something bigger on the roadmap you'd want help with. Happy to go wherever it's most useful.

[pradeeban]

@bhuvan-somisetty thanks, yes, I am reviewing and merging your PRs. concore is "officially" considered a "mature" project. So it is a bit challenging to think of anything drastically new. Your approach makes sense to me. But we will add more ideas to GSoC 2027 ideas page from concore/CONTROL-CORE if something changes. Overall, we aim to have 15 project ideas for GSoC 2027 as Alaska.

[bhuvan-somisetty]

Got it, that makes sense. I'll keep going with fixes and tests then, there's still plenty to tighten up around the CLI and runtimes. And I'll keep an eye on the GSoC 2027 ideas page, would love to take a shot at one of the concore ideas once it's up. Thanks!