Add JSON output mode to concore validate

[Titas-Ghosh]

Hi @pradeeban,
While working with the CLI and thinking through future editor/API integration, I noticed that concore validate currently only emits terminal friendly text output. That works well for humans, but it makes it harder for other parts of the stack to consume validation results in a reliable way.
I think it would be useful to add a machine readable output mode, for example:

concore validate workflow.graphml --format json

The goal would be to keep the current text output as the default, and add an optional JSON mode that returns structured validation results such as:

• overall validity
• errors/warnings/info entries
• stable error_type values
• node_id where applicable
• summary counts

This would make validation easier to consume programmatically without changing existing CLI behavior.

[Titas-Ghosh]

I’ve opened the PR #533 for this, whenever you get a chance, i’d be grateful if you could take a look. I do understand that the line changes are a bit higher here. If you feel the current shape is not ideal ,i am happy to adjust the approach accordingly, or even close this PR for now if that would be better.

Also, thank you to all the mentors @pradeeban,@mayureshkothare,@Rahuljagwani and all other contributors for the support throughout the contribution period. It has been genuinely encouraging to learn the codebase in such a collaborative environment.

It’s also nice to see the protocol conformance work of mine continue to move forward. Watching others build on that direction makes me feel that the original idea was useful, which is really motivating.

[pradeeban]

Thanks, good work @Titas-Ghosh. I will review and merge.