chore: merge origin/main, resolve VERSION + CHANGELOG conflicts

Bump to v0.15.13.0 (above main's 0.15.12.0). Resolve preamble.ts
conflicts (keep both vendoring detection and spawned session check).
Regenerate all SKILL.md files from resolved sources.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -403,6 +403,29 @@ Also when running targeted E2E tests to debug failures:
 - Never `pkill` running eval processes and restart — you lose results and waste money
 - One clean run beats three killed-and-restarted runs
 
+## Publishing native OpenClaw skills to ClawHub
+
+Native OpenClaw skills live in `openclaw/skills/gstack-openclaw-*/SKILL.md`. These are
+hand-crafted methodology skills (not generated by the pipeline) published to ClawHub
+so any OpenClaw user can install them.
+
+**Publishing:** The command is `clawhub publish` (NOT `clawhub skill publish`):
+
+```bash
+clawhub publish openclaw/skills/gstack-openclaw-office-hours \
+  --slug gstack-openclaw-office-hours --name "gstack Office Hours" \
+  --version 1.0.0 --changelog "description of changes"
+```
+
+Repeat for each skill: `gstack-openclaw-ceo-review`, `gstack-openclaw-investigate`,
+`gstack-openclaw-retro`. Bump `--version` on each update.
+
+**Auth:** `clawhub login` (opens browser for GitHub auth). `clawhub whoami` to verify.
+
+**Updating:** Same `clawhub publish` command with a higher `--version` and `--changelog`.
+
+**Verification:** `clawhub search gstack` to confirm they're live.
+
 ## Deploying to the active skill
 
 The active skill lives at `~/.claude/skills/gstack/`. After making changes: