feat(usability): confirm saves and guard booking submissions against duplicates (U07)

src/Duempelkas.App/Pages/Accounts/AccountDetail.razor

@@ -11,6 +11,12 @@
     <OperationNotice Result="fileResult" />
     @if (fileBusy) { <p role="status" aria-live="polite">Dateiaktion läuft … Bitte warten.</p> }
 
+    @if (lastSaved != null)
+    {
+        <div class="alert alert-success" role="status" aria-live="polite">
+            @lastSaved.Kind über @FormatAmount(lastSaved.Amount) @(lastSaved.Edited ? "aktualisiert" : "gespeichert").
+        </div>
+    }
     @if (savedOutsideYear.HasValue)
     {
         <div class="alert alert-info" role="status">
@@ -39,7 +45,7 @@
             <button class="btn btn-secondary btn-nav" @onclick="NavigateBack">
                 <i class="bi bi-arrow-left"></i> Zurück
             </button>
-                <button class="btn btn-success btn-nav" @onclick="() => showAddEntry = true">
+            <button class="btn btn-success btn-nav" @onclick="() => showAddEntry = true">
                 <i class="bi bi-plus-lg"></i> Einnahme oder Ausgabe erfassen
             </button>
             <button class="btn btn-info btn-nav" @onclick="() => showAddTransfer = true">
@@ -48,7 +54,7 @@
             <button class="btn btn-dark btn-nav" @onclick="HandleExport" disabled="@fileBusy">
                 <i class="bi bi-file-earmark-pdf"></i> Als PDF speichern
             </button>
-                <button class="btn btn-nav btn-primary" @onclick="OpenYearFilterDialog">
+            <button class="btn btn-nav btn-primary" @onclick="OpenYearFilterDialog">
                 <i class="bi bi-funnel"></i> @GetFilterLabel()
             </button>
         </div>
@@ -103,7 +109,7 @@
         @if (entries != null)
         {
             <div class="entries-scroll-wrapper">
-                <EntryTable Entries="entries" EmptyMessage="emptyEntriesMessage" OnDeleteEntry="RequestDeleteEntry" OnRestoreEntry="RequestRestoreEntry" OnEditEntry="RequestEditEntry" />
+                <EntryTable HighlightedEntryId="lastSaved?.EntryId" Entries="entries" EmptyMessage="emptyEntriesMessage" OnDeleteEntry="RequestDeleteEntry" OnRestoreEntry="RequestRestoreEntry" OnEditEntry="RequestEditEntry" />
             </div>
         }
     }