fix(openclaw): make native skills codex-friendly (#864)

Normalizes YAML frontmatter on the 4 hand-authored OpenClaw skills so stricter
parsers like Codex can load them. Codex CLI was rejecting these files with
"mapping values are not allowed in this context" on colons inside unquoted
description scalars.

- Drops non-standard `version` and `metadata` fields
- Rewrites descriptions into simple "Use when..." form (no inline colons)
- Adds a regression test enforcing strict frontmatter (name + description only)

Verified live: Codex CLI now loads the skills without errors. Observed during
/codex outside-voice run on the eval-community-prs plan review — Codex stderr
tripped on these exact files, which was real-world confirmation the fix is needed.

Dropped the connect-chrome changes from the original PR (the symlink removal is
out of scope for this fix; keeping connect-chrome -> open-gstack-browser).

Co-Authored-By: Cathryn Lavery <cathrynlavery@users.noreply.github.com>
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

openclaw/skills/gstack-openclaw-investigate/SKILL.md

@@ -1,8 +1,6 @@
 ---
 name: gstack-openclaw-investigate
-description: Systematic debugging with root cause investigation. Four phases: investigate, analyze, hypothesize, implement. Iron Law: no fixes without root cause. Use when asked to debug, fix a bug, investigate an error, or root cause analysis. Proactively use when user reports errors, stack traces, unexpected behavior, or says something stopped working.
-version: 1.0.0
-metadata: { "openclaw": { "emoji": "🔍" } }
+description: Use when asked to debug, fix a bug, investigate an error, or do root cause analysis, and when users report errors, stack traces, unexpected behavior, or say something stopped working.
 ---
 
 # Systematic Debugging