docs(plan): add task 04b for unfilled chapters collection

Task 04 defined the chapters collection; nothing ever filled it. Task 08
built RouteCard/GridGroup and found no data and no href/cta field to feed
them. Blocks 12 and 13.

plans/astro-refactor/task-04b-chapters-data.md

@@ -0,0 +1,60 @@
+# Task 04b — Chapter and landing content
+
+**Agent**: `content-i18n-migrator` · **Model**: MiniMax-M3 **Depends on**: 04 ·
+**Parallel with**: 14, 15, 16, 17 · **Blocks**: 12, 13 **Worktree**:
+`.agents/scripts/worktree.sh start 04b chapters-data`
+
+## Why this task exists
+
+It is not in the original plan. Task 04 defined the `chapters` collection and
+tasks 05–06 filled `skillSources`, `phases`, `providers`, `efforts`,
+`handsOnPrompts`, `skillInstallPrompts`, and `reviews` — but nothing ever filled
+`chapters`. `src/content/chapters/` does not exist, so the collection is defined
+and empty. Task 08 hit this from the other side: it built `RouteCard` and
+`GridGroup` and then had no data to feed them.
+
+Two tasks are blocked on it, so it is worth doing on its own rather than
+smuggling it into either.
+
+## Scope
+
+`src/content/config.ts` (the `chapters` schema only) and
+`src/content/chapters/*.json`. **You own `config.ts`** — you are the only agent
+who may edit it. Do not touch any other collection's schema.
+
+## Two things to deliver
+
+### 1. The landing route map has nowhere to live
+
+`index.html` has six cards, each with a destination and its own call-to-action
+text. The current `chapters` schema has `cards[]` with `label`/`title`/`copy`
+and no `href`, and no CTA field anywhere.
+
+Add what the real markup needs. From task 08's report, the six CTAs are not
+uniform — four read "Open chapter →", one "Open lab →", one "Open desk →", so a
+single hardcoded default would be wrong. Verify that against `index.html`
+yourself rather than trusting it.
+
+### 2. The four chapter pages have no entries
+
+Fill `chapters` for `/models/`, `/agents/`, `/skills/`, `/summary/` plus the
+landing page, both locales, from the existing HTML.
+
+## Rules that bite here
+
+- **Both `en` and `pt` are mandatory on every localized field.** A missing `pt`
+  must fail the build. Do not make a field optional to get past a validation
+  error — find the real Portuguese string in the existing HTML.
+- Copy strings **verbatim** from the current HTML. This is a move, not a
+  rewrite. No fixing typos, no improving phrasing, no translating anything that
+  is already translated.
+- Do not migrate any page. Tasks 12 and 13 own that. You produce data only.
+- Do not edit `verify.mjs`, `tokens.css`, `astro.config.mjs`, or any component.
+
+## Done when
+
+- [ ] `chapters` schema carries the landing route map's real fields
+- [ ] Entries exist for landing + the four chapter pages, both locales
+- [ ] Every string traceable to the HTML it came from
+- [ ] `pnpm run gate` green, 42 assertions intact
+- [ ] Report names the exact schema change so tasks 12 and 13 can rely on it