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

Services/OverlayService.cs

@@ -29,7 +29,7 @@ namespace decePubClient.Services
 
 		public async Task CloseTop(CancellationToken cancellationToken = default)
 		{
-			Entry top;
+			var top = default(Entry);
 			lock (open)
 				top = open.LastOrDefault();
 			if (top is null)
@@ -40,7 +40,7 @@ namespace decePubClient.Services
 
 		public async Task CloseAll(CancellationToken cancellationToken = default)
 		{
-			Entry[] all;
+			var all = default(Entry[]);
 			lock (open)
 			{
 				all = [.. open];