bug(skills): (optional) persists in filled headers

[KemingHe]

What Happened?

Expected: When an agent fills in an optional section, the "(optional)" label is stripped from the section header. When an agent omits an optional section, the entire section (header + placeholder content) is removed from the output.

Actual: "(optional)" persists in section headers regardless of whether the section was populated or omitted, producing headings like "### Related (optional)" in the final output.

Steps to Reproduce

1. Use github-issue skill to draft a feature request with Related and Alternatives Considered sections populated
2. Observe the generated output - section headers still read "(optional)"

Environment

• Affected skills: github-issue v3.0.0, github-pull-request v3.0.0, meeting-memo v2.0.0
• Affected templates:
  • .github/ISSUE_TEMPLATE/feature-request.md (Related, Alternatives Considered)
  • .github/ISSUE_TEMPLATE/bug-report.md (Related, Environment)
  • .github/pull_request_template.md (Impact, Notes)
  • agent-skills/meeting-memo/assets/memo-template.md (REFERENCES, GLOSSARY)
• Root cause: none of the three skill SKILL.md files include an instruction to strip the "(optional)" suffix when populating a section, or to omit the section when leaving it empty
• Fix: add a constraint to each affected skill instructing the agent to:
  (a) strip " (optional)" from the header when the section is populated, and
  (b) omit the entire section (header + placeholder body) when the section is not used