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

Extensions/GenericExtensions.cs

@@ -30,15 +30,6 @@ public static class GenericExtensions
 		};
 	}
 
-	// a count as a phone's narrow action buttons show it: 999, 1.2k, 12k, 1.2M
-	public static string Compact(this int count) => count switch
-	{
-		< 1000 => count.ToString(CultureInfo.CurrentCulture),
-		< 10_000 => (count / 1000d).ToString("0.#", CultureInfo.CurrentCulture) + "k",
-		< 1_000_000 => (count / 1000).ToString(CultureInfo.CurrentCulture) + "k",
-		_ => (count / 1_000_000d).ToString("0.#", CultureInfo.CurrentCulture) + "M"
-	};
-
 	public static string GetFileSize(this long size, CoalescingStringLocalizer localizer) => size switch
 	{
 		>= 1_048_576 => localizer["{0}MB", size / 1_048_576],