feat(content): define bilingual content collection schema

Add src/content/config.ts with strict { en, pt } schema and eight
typed collections matching the shapes in app.js and
skills-review/catalog.js: phases, providers, efforts, skillSources,
handsOnPrompts, skillInstallPrompts, chapters, reviews.

Both locales are required on every localized field. A deliberately
missing pt fails the build with InvalidContentEntryDataError, proved
with a probe entry and reverted. Silent English fallback is what turns
a bilingual site monolingual; the schema must not allow it.

Did not move any content yet. Tasks 05 and 06 fill the entries
against the shape defined here, in parallel.

Also records the language-switching decision in the task brief:
client-side swap, both locales in the payload, html lang tracks the
active language. Behaviour parity, schema fit, and tiny payload
size beat the SEO upside of route-based i18n for this site.

astro check: 0 errors, 0 warnings. npm run verify: green. No
assertion count change.

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

src/content/config.ts

@@ -0,0 +1,164 @@
+// Bilingual content schema for the Astro migration.
+//
+// Both `en` and `pt` are required on every localized field. A missing `pt`
+// must fail the build — silent English fallback is how a bilingual site
+// quietly becomes monolingual. Do not change `localized` to make a field
+// optional without an explicit reason in a code review.
+//
+// Layout follows the brief in plans/astro-refactor/task-04-content-schema.md:
+//   - phases / providers / efforts / skillSources / handsOnPrompts /
+//     skillInstallPrompts — guide content carried over from app.js
+//   - chapters              — copy for /models/, /agents/, /skills/, /summary/
+//   - reviews               — the 24 entries from skills-review/catalog.js
+//
+// This file is schema only. Tasks 05 and 06 fill the entries; the content
+// migrator agent owns this file end-to-end.
+
+import { defineCollection, z } from 'astro:content';
+
+// One localized field. `en` and `pt` are mandatory strings; no nullish,
+// no default. A missing `pt` is a build error, not a silent fallback.
+const localized = z.object({ en: z.string(), pt: z.string() });
+
+// Phases from `phases` in app.js: plan / build / review. Each phase has a
+// model recommendation, title, prose, and a code-flavoured summary line.
+const phases = defineCollection({
+  type: 'data',
+  schema: z.object({
+    id: z.string(),
+    model: localized,
+    title: localized,
+    copy: localized,
+    code: localized,
+  }),
+});
+
+// Providers from `modelGuide.providers` in app.js: openai / claude / gemini.
+// Tiers are a 3-tuple of [kind label, name, note-localized].
+const providers = defineCollection({
+  type: 'data',
+  schema: z.object({
+    id: z.string(),
+    label: z.string(),
+    source: z.string().url(),
+    title: localized,
+    copy: localized,
+    tiers: z.array(z.tuple([z.string(), z.string(), localized])),
+    config: z.string(),
+  }),
+});
+
+// Efforts from `modelGuide.efforts` in app.js: low / medium / high. Each
+// effort carries three lines per locale (heading, body, code-line).
+const efforts = defineCollection({
+  type: 'data',
+  schema: z.object({
+    id: z.string(),
+    en: z.array(z.string()),
+    pt: z.array(z.string()),
+  }),
+});
+
+// Skill source URLs from `skillSources` in app.js: pinned commit URLs for
+// each public skill this site references.
+const skillSources = defineCollection({
+  type: 'data',
+  schema: z.object({
+    id: z.string(),
+    url: z.string().url(),
+  }),
+});
+
+// Hands-on prompts from `handsOnPrompts` in app.js: per-locale basic and
+// skills variants for the Tiny Tasks exercise.
+const handsOnPrompts = defineCollection({
+  type: 'data',
+  schema: z.object({
+    id: z.string(),
+    en: z.object({ basic: z.string(), skills: z.string() }),
+    pt: z.object({ basic: z.string(), skills: z.string() }),
+  }),
+});
+
+// Skill install prompts from `skillInstallPrompts` in app.js: per-locale
+// install instructions that name the pinned commits and the safety rules.
+const skillInstallPrompts = defineCollection({
+  type: 'data',
+  schema: z.object({
+    id: z.string(),
+    en: z.string(),
+    pt: z.string(),
+  }),
+});
+
+// Chapter copy for /models/, /agents/, /skills/, /summary/. The body of
+// each page composes one or more sections; the field names mirror what the
+// existing HTML already says aloud (eyebrow / lede / card titles).
+const chapters = defineCollection({
+  type: 'data',
+  schema: z.object({
+    id: z.string(),
+    eyebrow: localized,
+    title: localized,
+    lede: localized,
+    cards: z
+      .array(
+        z.object({
+          label: localized,
+          title: localized,
+          copy: localized,
+        }),
+      )
+      .optional(),
+    sections: z
+      .array(
+        z.object({
+          eyebrow: localized.optional(),
+          title: localized,
+          copy: localized.optional(),
+          steps: z
+            .array(
+              z.object({
+                label: localized,
+                copy: localized,
+              }),
+            )
+            .optional(),
+        }),
+      )
+      .optional(),
+  }),
+});
+
+// Review desk entries from skills-review/catalog.js +
+// skills-review/submitted-catalog.js: 24 in total. `improved` is Markdown
+// source text, kept as a string here so the diff view that compares
+// original-vs-improved still has the raw text available. When the
+// markdown render path lands, this can become a body field without
+// changing the entry shape.
+const reviews = defineCollection({
+  type: 'data',
+  schema: z.object({
+    id: z.string(),
+    author: z.string(),
+    path: z.string(),
+    title: z.string(),
+    status: z.string(),
+    focus: z.string(),
+    wins: z.array(z.string()),
+    improve: z.array(z.string()),
+    extras: z.string(),
+    improved: z.string(),
+  }),
+});
+
+export const collections = {
+  phases,
+  providers,
+  efforts,
+  skillSources,
+  handsOnPrompts,
+  skillInstallPrompts,
+  chapters,
+  reviews,
+};