chore: consolidate the skill packages under .agents/

The repository had two skill directories. `skills/` held the four written
for this project; `.agents/skills/` held the ones the agent context refers
to. Nothing said which an agent should read, and `.agents/ORCHESTRATOR.md`
only ever pointed at the second.

Move the first four into `.agents/skills/` so there is one location, and
add the vendored packages this chapter work used: `animation-vocabulary`
and `improve-animations` (emilkowalski/skills), `teach` (mattpocock/skills),
plus a local `translation` skill and `audit-translations.mjs` for the EN/PT
pairs.

`skills-lock.json` pins the vendored three by source and content hash, so a
later re-vendor is a diff rather than a guess. `.claude/skills/` is
symlinks into `.agents/skills/`, which is what makes them loadable here
without a second copy on disk.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

.agents/skills/editorial-playbook/evals/evals.json

@@ -0,0 +1,10 @@
+[
+  {
+    "prompt": "Add a new bilingual chapter to a dependency-free static explainer with one diagram and one copy control. What should you decide and verify first?",
+    "expected_behavior": "Create a chapter map and content model first; pair EN/PT strings; use a small accessible interaction; verify mobile, Full HD, and 4K behavior."
+  },
+  {
+    "prompt": "The explainer needs 20 more sections but has no data source for section metadata. Recommend a lightweight implementation.",
+    "expected_behavior": "Keep content in structured data and render shared editorial primitives; recommend plain HTML/CSS/JS for a small static site, or Astro/MDX when shared build-time content collections justify it."
+  }
+]