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/Daisy/DataInput/DFilter.razor

@@ -7,19 +7,16 @@
 <div @attributes="InputAttributes" class="@Cx("filter", CssClass)">
 	<input type="radio" name="@GroupName" class="@Cx("btn", "filter-reset", SizeClass)" aria-label="@ResetText"
 		   disabled="@Disabled" @onchange="() => CurrentValue = default" />
-	@if (Options is not null)
+	@foreach (var option in Options)
 	{
-		foreach (var option in Options)
-		{
-			<input type="radio" name="@GroupName" class="@Cx("btn", SizeClass)" aria-label="@(TextOf?.Invoke(option) ?? option?.ToString())"
-				   checked="@IsSelected(option)" disabled="@Disabled"
-				   @onchange="() => CurrentValue = option" />
-		}
+		<input type="radio" name="@GroupName" class="@Cx("btn", SizeClass)" aria-label="@(TextOf?.Invoke(option) ?? option?.ToString())"
+			   checked="@IsSelected(option)" disabled="@Disabled"
+			   @onchange="() => CurrentValue = option" />
 	}
 </div>
 
 @code {
-	[Parameter] public IEnumerable<TValue> Options { get; set; }
+	[Parameter] public IEnumerable<TValue> Options { get; set; } = [];
 	/// <summary>An option's button text; ToString() when null.</summary>
 	[Parameter] public Func<TValue, string> TextOf { get; set; }
 	[Parameter] public string ResetText { get; set; } = "×";