House rules: numbers through one formatter, no made-up server errors, and the rules fail the build

- Every number shown on a page goes through NumbersExtensions: counts,
  percentages, the nerd readouts and the values written into a style.
- A failure the client builds itself (offline, timeout, retries run out, an
  answer it can't read) is a 400 that names its kind; only a server's own 5XX
  passes through.
- Login, sign-up, recovery and password confirmations leave autocomplete to
  the browser, so it can offer the saved login.
- The Daisy components start with empty lists and attributes, and a
  decorative image still renders alt="".
- Arasaka.HouseRules.Analyzers checks all of this in every build, together
  with PrivaPub.ClientModels.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01W4YtEJrgxG12Pc39Fai8Bd

Components/Admin/StatisticsPanel.razor

@@ -43,7 +43,7 @@
 		<DStats class="w-full overflow-x-auto neo-raised neo-xs" data-statistics-overview data-scroll-x>
 			<DStat>
 				<Heading>@Localizer["Deliveries that arrived"]</Heading>
-				<ChildContent>@(overview.DeliverySuccess is { } success ? $"{success * 100:0.#}%" : "—")</ChildContent>
+				<ChildContent>@(overview.DeliverySuccess is { } success ? (success * 100).ToDefaultPercent() : "—")</ChildContent>
 				<Desc>@Localizer["p50 {0} ms, p95 {1} ms", Ms(overview.DeliveryLatencyMs.P50), Ms(overview.DeliveryLatencyMs.P95)]</Desc>
 			</DStat>
 			<DStat>