Quote argument-hint values in SKILL.md frontmatter

[thejesh23]

Bug

Two SKILL.md files use unquoted square brackets in their argument-hint: YAML frontmatter:

• .claude/skills/create-html-mock/SKILL.md: argument-hint: [feature description]
• .claude/skills/extract-requirements-from-mock/SKILL.md: argument-hint: [feature-name]

Per YAML 1.2 flow syntax, [X] parses as a sequence (array), not a string. Tools that consume this frontmatter and require argument-hint to be a string will reject or misrender these skills.

Impact

GitHub Copilot CLI 1.0.65 requires argument-hint to be a string and rejects arrays. There is also a latent equivalent issue tracked for Claude Code in anthropics/claude-code#22161.

Fix

Quote the values so YAML parses them as strings:

-argument-hint: [feature description]
+argument-hint: "[feature description]"

-argument-hint: [feature-name]
+argument-hint: "[feature-name]"

The rendered hint ([feature description], [feature-name]) is unchanged — only the YAML type changes from sequence to string.

The other three SKILL.md files in .claude/skills/ use <feature-name> (angle brackets), which YAML already parses as a string, so they need no change.

Test plan

• python3 -c "import yaml; ..." on both files: argument-hint now parses as str ('[feature description]', '[feature-name]') instead of list.
• Load the skills in GitHub Copilot CLI 1.0.65 and confirm they no longer error on the frontmatter.
• Verify the argument hint still displays as [feature description] / [feature-name] in tool UIs.

[thejesh23]

Tracking issue: #61 — captures the bug diagnosis and reproducer separately for anyone searching the repo who lands there before this PR.