chore(upstream): sync latest pstack

[3metaJun]

The pstack upstream has advanced, leaving mstack's bundled skills, guides, automations, and runtime metadata behind.

This updates the pstack pin to 11713c6, imports the new ketchup skill, refreshes the tracked upstream artifacts and manifest, and preserves mstack-specific portability adaptations. Cursor-only frontmatter is removed from the imported skill.

Verification:

• npm test (719 tests: 718 passed, 1 skipped)
• node scripts/validate.mjs
• node scripts/skill-baseline.mjs --source ../pstack-sync/pstack --matt-source ../matt-skills-sync --check
• git diff --check

---

Agent: gpt-5 via pi

[3metaJun]

I found two actionable issues; I do not recommend merging yet.

1. [blocking] The upstream validation job still checks out the old pstack commit. profiles/upstreams.json now pins 11713c683fe4add4fd403ea880580abbc9e0875f (line 4), but .github/workflows/validate.yml still passes ref: 2cbf58508f40de470d7490b55c51d71241928fa2 to the checkout step. The upstream check therefore fails with “Source checkout is at 2cbf585..., profile pins 11713c...”, as seen in the current PR checks. Update the workflow ref (and any equivalent source pin) together with this sync.

2. [compatibility] This PR removes two guide pages from the guide index without updating existing inbound links. docs/guide/README.md removes 11-mixed-harness.md and 12-claude-code-routing.md, but README.md:131, README.md:553, and docs/harness-adapters.md:130,175 still link to those paths. Those links become 404s in the published repository/package. Either retain the pages or update/remove every inbound reference.

The other checks are green, but the upstream job is failing and the stale links are a user-facing regression. Please address these before merge.

[3metaJun]

Addressed the blocking review finding: .github/workflows/validate.yml now checks out pstack at 11713c683fe4add4fd403ea880580abbc9e0875f, matching profiles/upstreams.json.

The two guide pages mentioned in the review are still present in the repository and package; the guide index no longer lists them, but existing inbound links remain valid. No link changes were needed.

The full local suite passed before this CI-only change; waiting for the updated CI run before merge.