Description

This PR adds an RFC issue template for proposing design or architectural changes, and improves the issue-check workflow with better messaging and RFC support.

Currently, contributors who want to propose larger changes don't have a dedicated template. Additionally, the no-template warning message is unclear and doesn't guide users on how to fix the issue.

Changes

Issue Templates

• rfc.yml: New minimal RFC template with a single free-form Proposal field — no structured format required

GitHub Action

• issue-check.yml:
  • Skip completeness check entirely for issues with rfc label (free-form by design)
  • Update no-template warning to a friendlier, actionable message that tells users to add the appropriate label and edit the issue to match the template fields — instead of the previous unclear error message

Before vs After (no-template message)

Before:

⚠️ Could not detect an issue template. Please make sure this issue was created using one of the available templates and that the corresponding label (bug, feature, documentation, guidance) is present.

After:

Thanks for the report! It looks like this issue was created without a template and is missing some required fields. Please add one of the following labels: bug, feature, documentation, or guidance, then edit this issue to include the matching template fields — the incomplete label will be removed automatically.