Declare the vendored skills and check the declaration

What

The vendored set is now declared, and a gate checks the declaration. vendor/gitlab-ai-skills/include.yml lists the ten skills skills/gitlab-simulation routes to, each with a reason and the files that route to it. vendor-sync vendors exactly that list. Nine others are dropped: handoff, write-large-file, pushify, run-in-tmux-pane, authoring-skills, playwright-cli, opencode-refine, self-service-performance-testing and gitlab-clickhouse.

flowchart LR
  A["include.yml<br/>declared skills"] --> B["vendor-sync"]
  B --> C["vendored dirs and<br/>skills/ symlinks"]
  A --> D{"vendor-check"}
  C --> D
  E["routes in<br/>skills/gitlab-simulation"] --> D
  D --> F["just ci fails on<br/>any disagreement"]

Why

Nine skills loaded into every install with nothing pointing at them. ADR-0008 records the decision.

Notes

• The pin is unchanged. vendor-sync at c5272c9 regenerates manifest.yml byte for byte.
• The routing battery in sims/ was recorded against all nineteen; a dated note says so. It needs no re-run, because the skill description is unchanged.