feat(usability): preserve reporting year and locate outside-period bookings (U04)

src/Duempelkas.App/Pages/Dashboard.razor.cs

@@ -14,7 +14,7 @@ public partial class Dashboard
     private bool showEditClubName;
     private bool showRestoreConfirm;
     private bool showYearFilterDialog;
-    private int? selectedYear = DateTime.Now.Year;
+    private int? selectedYear { get => Period.Year; set => Period.Year = value; }
     private List<int> availableYears = [];
     private string clubName = string.Empty;
     private string? savedPdfPath;
@@ -67,7 +67,7 @@ public partial class Dashboard
     private async Task LoadAll()
     {
         await LoadAccounts();
-        availableYears = await EntryService.GetAllEntryYearsAsync();
+        availableYears = Period.Choices(await EntryService.GetAllEntryYearsAsync());
     }
 
     private async Task LoadAccounts()
@@ -207,7 +207,7 @@ public partial class Dashboard
         return amount.ToString("N2", CultureInfo.GetCultureInfo("de-DE")) + " €";
     }
 
-    private string GetFilterLabel() => selectedYear?.ToString() ?? "Alle";
+    private string GetFilterLabel() => Period.Label;
 
     private string ThemeButtonLabel => currentTheme == "dark" ? "Hell" : "Dunkel";