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/translation/SKILL.md

@@ -0,0 +1,116 @@
+---
+name: translation
+description:
+  Translate site copy to Brazilian Portuguese in a register and vocabulary that
+  match the existing translated collections. Use when adding a new localized
+  field, auditing a chapter for missing or identical en/pt pairs, or proposing
+  translation candidates for review. Always pair with
+  [`../../rules/content-i18n.md`](../../rules/content-i18n.md).
+---
+
+# Translation
+
+This site is bilingual EN/PT-BR. The English is editorial; the Portuguese has to
+read like a native technical writer, not like a machine. The glossary
+([`references/glossary.md`](references/glossary.md)) and tone notes
+([`references/tone.md`](references/tone.md)) pin the conventions so any agent —
+me, a different LLM, a future you — produces Portuguese that matches what is
+already there.
+
+## Before anything
+
+Read [`../../rules/content-i18n.md`](../../rules/content-i18n.md) and
+[`../../context/content-i18n.md`](../../context/content-i18n.md). Both are
+binding. In particular:
+
+- Both `en` and `pt` are required on every `localized` field. A missing `pt`
+  must fail the build.
+- These are hand-written translations with deliberate tone. **Copy, do not
+  retype.** Retyping introduces drift.
+- The site's bilingual contract is client-side: both languages ship in the
+  payload, the toggle swaps visibility. Do not propose `/en/` `/pt/` routing
+  without a separate decision.
+
+## Audit before you propose
+
+Run the audit script first. It walks `src/content/**` and reports every
+`localized` field where `en === pt`:
+
+```bash
+node .agents/scripts/audit-translations.mjs
+```
+
+The script exits non-zero on any identical pair. That is the list you work from
+— chapter, file, field. Touch only what's flagged, and only after a human has
+reviewed your proposal for the first chapter (the tone is contagious: if the
+first chapter is right, the rest fall into the same voice).
+
+## Propose, do not commit
+
+This skill is **review-first**. The workflow is:
+
+1. Pick the smallest chapter (today: `landing.json`, 30 fields). Read the
+   English, read the existing translations in the other collections to absorb
+   the voice, then write candidates.
+2. Show the diff to a human reviewer. They sign off on tone, terminology, and
+   register before you proceed to the next chapter.
+3. Only after the reviewer agrees, write the JSON. Re-run the audit; it must
+   pass.
+4. Repeat for the next chapter.
+
+Auto-committing a translation in bulk is the same failure mode as a content
+migration that "passes" by deleting assertions: silent monolingualism. The
+review step is the whole point.
+
+## What stays in English
+
+Some terms are kept in English by deliberate convention. Do not translate:
+
+- Code identifiers, file paths, command names, product names (`SKILL.md`,
+  `AGENTS.md`, `.agents/skills/`, `git`, `pnpm`, `claude`, `opus`, `sonnet`,
+  `haiku`, `gpt-5.6`, `sol`, `terra`, `luna`)
+- Product surface nouns that the team has decided to keep: `skill`, `worktree`,
+  `worker`, `branch`, `merge`, `commit`, `diff`, `brief`, `gate`, `pipeline`,
+  `recall`, `prompt`
+- The `<i></i>` and `<b></b>` glyphs that ship in copy — they are decorative and
+  the stylesheet depends on them
+- Arrows used as connectors (`→`, `↗`) — keep them, the spacing is intentional
+
+The full list is in the glossary.
+
+## What to translate
+
+Everything else, including:
+
+- Section titles, ledes, eyebrows
+- Card titles, body copy, call-to-action labels
+- Stage / phase labels in prose ("PLAN", "BUILD", "REVIEW" stay uppercase
+  English because they are acronyms in the design system; the prose around them
+  translates)
+- Inline `<em>` emphasis and `<br>` line breaks — the structure is shared, the
+  words differ
+
+## Verification
+
+After writing, before committing:
+
+```bash
+pnpm run build                     # schema check (both locales present)
+node .agents/scripts/audit-translations.mjs   # en !== pt everywhere
+pnpm run verify                    # full gate, includes rendered snapshots
+```
+
+A rendered snapshot diff in `verify.mjs` catching a new Portuguese string is
+expected. Update `.agents/snapshots/*.txt` if the prose really did change and
+the snapshot was a stale capture. Do not delete assertions to make it pass.
+
+## What this skill does NOT do
+
+- Migrate content out of legacy `app.js` (that's `content-migration`)
+- Wire `lang` state into chapter pages (that's tasks 12 / 13 / 15)
+- Edit `src/content/config.ts` (the schema is `verification-engineer`'s scope)
+- Touch components, layouts, styles, or the legacy tree
+- Translate code, comments inside code blocks, command output, or paths
+
+The chapter's review-desk body (`src/content/reviews/*.md`) is intentionally not
+localized — the review desk is an English-only editor by design.