feat(blog): add the posts and media collections

Drafts are on so a post can be written across sittings without saving
being publishing.

afterChange and afterDelete revalidate every path a post appears on.
Blog pages are ISR because CI builds with no database, so without these
a published post would not appear until the revalidate window expired —
up to an hour of a writer concluding that publishing is broken. Payload
runs in the same process as Next, so these are direct revalidatePath
calls with no webhook and no shared secret.

Media writes to an absolute /app/media matching the compose mount; a
mismatch would write into the container filesystem, where the next
redeploy silently discards it. Alt text is required rather than
optional.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017YmbBhr8s7GusjDE12hrZM

nextjs-app/__tests__/payload/collections.test.ts

@@ -0,0 +1,64 @@
+/**
+ * Payload is ESM-only and next/jest will not transform it, so the collections
+ * cannot be imported and their sanitised config inspected here (see
+ * lib/payloadRoutes.ts for the full reasoning). These assert the source of the
+ * collection definitions instead — enough to catch the settings whose loss is
+ * silent, and cheap. Behaviour is proved by the e2e journeys against staging.
+ */
+import fs from 'fs';
+import path from 'path';
+
+const read = (file: string) =>
+  fs.readFileSync(path.join(__dirname, '..', '..', 'collections', file), 'utf8');
+
+const POSTS = read('Posts.ts');
+const MEDIA = read('Media.ts');
+const CONFIG = fs.readFileSync(
+  path.join(__dirname, '..', '..', 'payload.config.ts'),
+  'utf8',
+);
+
+describe('posts collection', () => {
+  it('supports drafts, so saving is not publishing', () => {
+    expect(POSTS).toMatch(/drafts:\s*true/);
+  });
+
+  it('has a unique, indexed slug for stable URLs', () => {
+    const slugField = POSTS.slice(POSTS.indexOf("name: 'slug'"));
+    expect(slugField).toMatch(/unique:\s*true/);
+    expect(slugField).toMatch(/index:\s*true/);
+  });
+
+  it('is publicly readable', () => {
+    expect(POSTS).toMatch(/access:\s*\{\s*read:\s*\(\)\s*=>\s*true/);
+  });
+
+  it('revalidates the blog paths when a post changes or is deleted', () => {
+    // Blog pages are ISR because CI builds with no database. Without these
+    // hooks a published post would not appear until the revalidate window
+    // expired — up to an hour of a writer thinking publishing is broken.
+    expect(POSTS).toContain('afterChange');
+    expect(POSTS).toContain('afterDelete');
+    expect(POSTS).toMatch(/revalidatePath\('\/blog'\)/);
+    expect(POSTS).toMatch(/revalidatePath\(`\/blog\/\$\{[^}]+\}`\)/);
+  });
+});
+
+describe('media collection', () => {
+  it('writes uploads to the mounted volume, by absolute path', () => {
+    // Must match the payload_media mount in docker-compose.portainer.yml.
+    // Payload 3 requires staticDir to be absolute.
+    expect(MEDIA).toMatch(/staticDir:\s*'\/app\/media'/);
+  });
+
+  it('requires alt text on every upload', () => {
+    const altField = MEDIA.slice(MEDIA.indexOf("name: 'alt'"));
+    expect(altField).toMatch(/required:\s*true/);
+  });
+});
+
+describe('payload config', () => {
+  it('registers every collection', () => {
+    expect(CONFIG).toMatch(/collections:\s*\[Users,\s*Posts,\s*Media\]/);
+  });
+});