docs(blog): how to publish, and why the app has two route groups

PUBLISHING.md carries the house style with the posts, so the standard
survives without the design doc to hand — including the rule that a post
states what a metric does not show, which is the strongest signal a
human wrote it.

CLAUDE.md gains the two constraints that are invisible from the code and
expensive to rediscover: metadata file conventions break if moved into a
route group, and the build must keep succeeding with DATABASE_URL unset.

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

nextjs-app/docs/PUBLISHING.md

@@ -0,0 +1,82 @@
+# Publishing to the blog
+
+The blog is Payload CMS, running inside the Next.js app. There is no separate
+service and no second deploy — writing a post is done in the browser and takes
+effect on the live site within seconds.
+
+## Signing in
+
+`https://www.schoolcompare.co.uk/admin` — one account, no registration. If you
+need the account seeded on a fresh environment, run against the container:
+
+```bash
+npx payload create-first-user
+```
+
+Staging has its own admin panel, its own database and its own credentials at
+`https://stx.schoolcompare.co.uk/admin`. Never reuse production's secret or
+password there.
+
+## Writing a post
+
+**Posts → Create New.** The fields:
+
+| Field | Notes |
+|---|---|
+| **Title** | The `<h1>` and the browser tab. |
+| **Slug** | The URL segment, in the sidebar. **Never change it after publishing** — it is the canonical URL, and changing it breaks every existing link and discards the page's accumulated search signal. |
+| **Published at** | The date shown on the post and in the feed. |
+| **Excerpt** | Max 200 characters. Shown on the index *and* used as the meta description, so write it as a standalone sentence rather than a teaser. |
+| **Hero image** | Optional. Becomes the social share image; without one, the site's generated card is used. |
+| **Content** | Rich text. `/` inserts a block. |
+
+**Save as draft** while you're working — drafts are not public. **Publish** when
+it's ready.
+
+### The callout block
+
+One custom block, `Callout`, with two tones:
+
+- **Caveat** — what a number does *not* show. This is the one that matters: it
+  is how a post states a limitation in context rather than burying it in a
+  closing paragraph.
+- **Note** — a useful aside.
+
+### Images
+
+Every image requires alt text; the editor will not let you save without it.
+Uploads go to a Docker volume on the host, which is backed up separately from
+Postgres — an image is not reproducible from the pipeline the way school data
+is.
+
+## How publishing reaches the live site
+
+- `/blog`, `/blog/rss.xml` and `/content-sitemap.xml` are rendered per request,
+  so a new post appears immediately.
+- `/blog/[slug]` is cached after its first request. Publishing or editing fires
+  a `revalidatePath` from the collection's `afterChange` hook, which drops that
+  cached copy — so edits appear immediately too.
+
+If a change doesn't show, it is far more likely the post is still a draft than
+that the cache is stale.
+
+## House style
+
+These rules are why the blog exists. A post that ignores them makes the site
+read more machine-generated, not less.
+
+- **First person singular.** "I built", "I found" — never "we provide".
+- **Concrete over general.** "When we were looking at schools in Wandsworth"
+  beats any amount of stated warmth.
+- **State limits before someone else finds them.** Every post that presents a
+  metric says what it does not show. This is the single strongest signal that a
+  human wrote it: generated content does not volunteer its own weaknesses.
+- **No mission statements, no "passionate about", no invented team.** There is
+  one person here.
+- **Short sentences.**
+- **Never publish a surname, an employer, or a child's name.** The site's author
+  is "Tudor". See `/about`.
+- **Never invent a figure**, even illustratively. On a site whose whole
+  proposition is official data, a made-up number attached to a real school is
+  the one thing it cannot do — and no illustrative intent survives being
+  screenshotted.