Adopt b2b.next's client patterns: services, page state, feedback

Ported from the owner's b2b.next and adapted from MudBlazor to the daisyUI
components:
- LocalizableComponentBase provides CascadingState, Navigation, Toast,
  IsLoading/IsDefaultDisabled, WhenOnline/StartOnlinePolling, and after-render
  jobs that actually run.
- CascadingState starts with initialised state and polls the online status
  with a PeriodicTimer. It reports errors through ILoggingService plus a toast,
  and disposes what it holds.
- New pieces:
  - ToastService + ToastHost, the snackbar, with AddResponseError/Success/
    Warning/Exception in SUtility;
  - ErrorViewer, which shows the validation messages plus AdditionalError(s);
  - LoggingService, which writes to the console and the IndexedDB client log.
- HttpService is rebuilt and registered:
  - auth levels Get/Post/Delete, *Anon and *TotallyAnon;
  - retry with backoff;
  - classified failures (FailureCodes) instead of exceptions;
  - HTTP 410 on cancel;
  - the "default" client.
  ReadWebResult and DefaultReadFromJsonAsync read its responses.
- ClientJsonContext is source-generated, and SUtility.DefaultSerializer and
  Blazored.LocalStorage use it.
- WebResult gains a C# 14 IsInvalid extension property.

The code follows the imported rules:
- Every service and async helper takes a CancellationToken last.
- Primary constructors replace constructor-plus-fields.
- MessagesService and IStorage return Task<WebResult> / Task<List<T>>.
  MessagesService is still mock, building its results in memory; the seed
  feed and thread moved to Faker.
- Index and ExpandMessage follow the page pattern: an offline guard with
  WhenOnline, LoadData, and early returns with toasts on the results they used
  to ignore. ExpandMessage reloads on route change and shows "not found"
  instead of a null message.
- Model and state collections are [], and the fake identity defaults moved
  out of the models.
- Components:
  - no ?. chains over initialised state;
  - [Inject] instead of @inject;
  - IsDefaultDisabled on the actions;
  - autocomplete on every text input;
  - Localizer[key, args] instead of string.Format;
  - the localizer no longer leaks its inner _pLocalizer.
- Settings → General gains a language picker (English/Italiano), and
  SetDefaultCulture limits the culture to those two.

Bugs fixed along the way:
- A compose with untouched (null) content passed the empty check.
- File errors were joined with <br/> and rendered as markup.
- ClientLogs.ErrorMessage() threw on warnings.
- CoalescingStringLocalizer[key, args] showed a raw "{0}" for missing keys.
- AppStatusService exposed a call to a JS function that doesn't exist.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LsXgEaXee4GCU1hwYgPJXw

Services/AppStatusService.cs

@@ -4,20 +4,12 @@ using Microsoft.JSInterop;
 
 namespace decePubClient.Services;
 
-public class AppStatusService
+public class AppStatusService(IJSRuntime jsRuntime)
 {
-		readonly IJSRuntime JsRuntime;
-		readonly IJSInProcessRuntime JsSyncRuntime;
+		readonly IJSInProcessRuntime JsSyncRuntime = (IJSInProcessRuntime)jsRuntime;
 
-		public AppStatusService(IJSRuntime JSRuntime)
-		{
-			JsRuntime = JSRuntime;
-			JsSyncRuntime = (IJSInProcessRuntime)JSRuntime;
-		}
-
-		public async ValueTask<bool> IsOnline() => await JsSyncRuntime.InvokeAsync<bool>("isOnline");
-
-		public bool InputCaptureSupported() => JsSyncRuntime.Invoke<bool>("inputCaptureSupported");
+		public async ValueTask<bool> IsOnline(CancellationToken cancellationToken = default) =>
+			await jsRuntime.InvokeAsync<bool>("isOnline", cancellationToken);
 
 		public bool IsServiceWorkerAvailable() => JsSyncRuntime.Invoke<bool>("isServiceWorkerAvailable");
 
@@ -31,15 +23,11 @@ public class AppStatusService
 
 		public void ClearAppBadge() => JsSyncRuntime.InvokeVoid("clearAppBadge");
 
-		public async ValueTask ClearCache()
-		{
-			await JsRuntime.InvokeVoidAsync("clearCache");
-		}
+		public async ValueTask ClearCache(CancellationToken cancellationToken = default) =>
+			await jsRuntime.InvokeVoidAsync("clearCache", cancellationToken);
 
-		public async ValueTask ClearLocalStorage()
-		{
-			await JsRuntime.InvokeVoidAsync("clearLocalStorage");
-		}
+		public async ValueTask ClearLocalStorage(CancellationToken cancellationToken = default) =>
+			await jsRuntime.InvokeVoidAsync("clearLocalStorage", cancellationToken);
 
 		public void ReloadPage()
 		{
@@ -55,7 +43,9 @@ public class AppStatusService
 
 		public bool CanShare() => JsSyncRuntime.Invoke<bool>("canShareStuff");
 
-		public async ValueTask ShareTextUrl(string title, string text, Uri uri) => await JsRuntime.InvokeVoidAsync("shareTextUrl", title, text, uri.ToString());
+		public async ValueTask ShareTextUrl(string title, string text, Uri uri, CancellationToken cancellationToken = default) =>
+			await jsRuntime.InvokeVoidAsync("shareTextUrl", cancellationToken, title, text, uri.ToString());
 
-		public async ValueTask ShareText(string title, string text) => await JsRuntime.InvokeVoidAsync("shareText", title, text);
+		public async ValueTask ShareText(string title, string text, CancellationToken cancellationToken = default) =>
+			await jsRuntime.InvokeVoidAsync("shareText", cancellationToken, title, text);
 }