Add YAML schemas for system tests components, tests, and metadata

[kishansinghifs1]

Add YAML schemas for components, tests, and metadata : #403

• Added JSON schemas and component templates to define and enforce the expected YAML structure.
• Configured mappings so the Red Hat YAML extension provides autocompletion, hover docs, and inline validation when editing these files.
• The component template schema documents the expected Docker Compose service fragment structure; note that Jinja2 template syntax ({{ }}, {% %}) will still produce warnings in the editor since it's not valid YAML.

Checklist:

• I added a summary of any user-facing changes (compared to the last release) in the changelog-entries/<PRnumber>.md.
• I will remember to squash-and-merge, providing a useful summary of the changes of this PR.

[precice-bot]

This pull request has been mentioned on preCICE Forum on Discourse. There might be relevant details there:

https://precice.discourse.group/t/gsoc-2026-kishan-singh-system-tests-improvements/2775/1

[MakisH]

Thank you for demonstrating that #403 is possible, @kishansinghifs1. It looks like it works for tests.yaml and components.yaml.

How did you generate the schema?

There have been several changes since this PR was opened (I could only look at it closer now), and we would anyway need to add the respective headers to all related YAML files.

Would you still like to pursue this PR?

[MakisH]

The schema header still needs to be added to the various component templates.

You write that

The component template schema documents the expected Docker Compose service fragment structure; note that Jinja2 template syntax ({{ }}, {% %}) will still produce warnings in the editor since it's not valid YAML.

What exactly breaks? It is still a regular comment, no?

[MakisH]

There have recently been some changes in the schema in develop since #842: the repository is now an optional property of each build_args (actually, a required one of any property ending in _REF).

[MakisH]

This would still need to be added to the respective metadata.yaml files, right? Or can we centrally make it being picked up automatically for every file?

[MakisH]

There have been a few new parameters since this was opened: max_time, max_time_windows, timeout.

[kishansinghifs1]

Thank you for demonstrating that #403 is possible, @kishansinghifs1. It looks like it works for tests.yaml and components.yaml.

How did you generate the schema?

There have been several changes since this PR was opened (I could only look at it closer now), and we would anyway need to add the respective headers to all related YAML files.

Would you still like to pursue this PR?

Sorry @MakisH due to the time constraint I would not be able to work further over the respective issue. Thank you!!