fix(skills): quote argument-hint YAML string

[thejesh23]

Summary

argument-hint in the SKILL.md frontmatter is documented as a string, but the current YAML uses an unquoted [...] value, which YAML parses as a flow sequence (list) rather than a string. Copilot CLI 1.0.65 tightened frontmatter validation and now rejects skills whose argument-hint is not a string, so this file breaks skill loading on that release.

Fix: quote the value as a YAML string. Because the hint contains double quotes ("frontend only", "include runtimes"), single quotes are used so the inner double quotes do not need escaping.

Before:

argument-hint: [optional scope, e.g. "frontend only" or "include runtimes"]

After:

argument-hint: '[optional scope, e.g. "frontend only" or "include runtimes"]'

The sibling skill .claude/skills/release/SKILL.md was already correct (argument-hint: "[version-or-tag]"), so no change there.

Context

• Latent equivalent on Claude Code: [BUG] argument-hint YAML frontmatter with brackets causes React error #31 and unrecoverable TUI hang anthropics/claude-code#22161
• Full tree scan (grep -rn "argument-hint:") found only one buggy file in this repo

Test plan

• python3 -c "import yaml; yaml.safe_load(open('.claude/skills/upgrade-deps/SKILL.md').read().split('---')[1])" returns a dict where argument-hint is a str, not a list
• Verified .claude/skills/release/SKILL.md still parses argument-hint as str (unchanged)
• Load the upgrade-deps skill with Copilot CLI >= 1.0.65 and confirm no frontmatter validation error
• Confirm existing Claude Code / other tooling still displays the hint identically (the rendered string is unchanged)

[thejesh23]

Tracking issue: #17 — captures the bug diagnosis and reproducer separately for anyone searching the repo who lands there before this PR.