Turn the status page into a full status page generator

Components can be put in groups and given public names. Public incidents carry
posts written for customers (the internal timeline stays internal), the
components they affect, and a page for each incident plus paged history.
Scheduled maintenance has its own window, shows affected components as under
maintenance, and is announced when scheduled, started, ended or canceled.

Branding (title, logo, accent checked for contrast, contact link, footer) and a
custom domain that serves only the status page. Visitors follow by RSS, by
confirmed email, or by webhook that must answer a test request. Admin UI for
all of it, tests, README and design notes.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

docs/design.md

@@ -14,7 +14,7 @@ Sandbar's pages follow the Lightwell design language, as Hammerhead does. The re
 | File | What it holds |
 | --- | --- |
 | `internal/sandbar/web/index.html` | The app. The token block sits between `tokens:begin` and `tokens:end`; raw colors are allowed only there. |
-| `internal/sandbar/web/status.html` | The public status page. Same token block, repeated. |
+| `internal/sandbar/web/status.html` | The public status page: home, history and incident pages in one file. Same token block, repeated. |
 
 Both are single files with no build step. Change a token in both, and in Hammerhead when the language changes.
 
@@ -31,6 +31,9 @@ The helpers at the top of the script in `index.html` are the same as Hammerhead'
 ## Status page bars and charts
 
 * **Uptime bars** on the public page are one bar per UTC day, 90 of them. Green is no failures, amber is at least 99% passing, red is below that, grey is no data. Color is never the only signal: the row carries a text status badge and the uptime percentage, each bar's tooltip says the date and the numbers in words, and the whole strip has an `aria-label` summary.
+* **Component states** are badges with text: Operational (success), Degraded performance and Partial outage (warning), Major outage (danger), Under maintenance (accent). A group heading shows the worst state of its components.
+* **Incident posts** are a short list with a rule on the left: the status in bold, the time, then the text, newest first. Maintenance windows use the same card with a Scheduled, In progress or Completed badge.
+* **Branding** changes one token only, `--accent`, which the page sets from the saved color. The admin form refuses colors that give white text less than 4.5 to 1, so the contrast rule survives any choice.
 * **Analytics charts** are plain bars made of tokens, with two series (visitors in the accent, page views in a lighter mix of it), a legend with text, a native tooltip per bar, and an `aria-label` that gives the totals. There are no chart libraries.
 * **Top lists** are tables with a proportional bar behind the name, so the numbers stay readable without the bar.