fix(skills): remove unquoted ": " from 10 SKILL.md descriptions

[5uck1ess]

Summary

• Fixes the YAML-parse bug in 10 skills/*/SKILL.md files where unquoted : sequences inside plain-scalar description: values violated YAML 1.2 §7.3.3, causing strict parsers to drop the description and Claude Code to fall back to the plugin-prefixed slash name + H1 heading.
• 8 files rephrased (when: → when —, flag: → flag —), 2 files (mega-pr, pr-ready) converted to folded block scalar (>-) because they contain inline slash paths like /devkit:tri-review and /commit-commands:commit-push-pr that are natural to keep.
• Verified with Ruby Psych strict YAML parser — all 10 files now load cleanly and return non-empty description strings.

Rationale for strategy split

• Rephrase is minimal-touch and preserves the 5-part description rubric. Used for the 8 files where the only offender was a conversational when: / flag:.
• Block scalar (>-) for mega-pr and pr-ready avoids contorting natural slash-path references. Folded style (>) collapses line breaks back to spaces so the runtime-observable description is unchanged, and strip chomping (-) avoids a trailing newline.

Affected files

File	Strategy	Offender(s) removed
skills/audit/SKILL.md	rephrase	flag: outdated
skills/bugfix/SKILL.md	rephrase	when: the
skills/deep-research/SKILL.md	rephrase	when: the
skills/feature/SKILL.md	rephrase	feature: ..., when: the
skills/refactor/SKILL.md	rephrase	when: the
skills/tri-debug/SKILL.md	rephrase	when: the
skills/tri-dispatch/SKILL.md	rephrase	when: the
skills/tri-security/SKILL.md	rephrase	when: touching
skills/mega-pr/SKILL.md	block scalar >-	when: the
skills/pr-ready/SKILL.md	block scalar >-	when: lint

Test plan

• ruby -ryaml -e 'YAML.safe_load(frontmatter)' for all 10 files → passes
• No leftover \w+: \S patterns in any rephrased file (confirmed via grep)
• On Windows Claude Code: /reload-plugins, confirm slash picker shows all 10 skills unprefixed with full descriptions instead of /devkit:<name> + H1 fallback
• On Mac Claude Code: /reload-plugins, confirm no regression (rendering stays identical)

Notes

Closes #87.

Issue #87's per-file token list included a few phantom offenders (research: c, enforce: s, docs: u, pipeline: v, Skill: d) that don't actually appear in the v2.1.20 files — they were artifacts of the scanning regex. The real count is 11 offending tokens across 10 files, all fixed by this PR.