Markdown-based issue templates with frontmatter were silently ignored
by GitHub (likely an empty-string assignees field or frontmatter
format issue). Switched to the newer YAML-based issue forms which use
a structured schema format that GitHub explicitly supports.
- bug_report.yml: structured form with required fields for description,
reproduction steps, environment, screenshots
- feature_request.yml: form with problem/motivation, proposed solution,
alternatives, mockups
- config.yml: unchanged, keeps blank_issues_enabled: false
