Refactor currency handling and UI updates

Updated currency handling to use dynamic symbols, defaulting to "€". Adjusted UI components to reflect these changes. Introduced `GetCurrencySymbol` and `NormalizeCurrencySymbol` methods for consistency. Reintroduced QR code parsing/serialization methods. Updated models and services to align with the new currency symbol logic.

src/BirthList.Web/Components/Pages/RegistryAdmin.razor

@@ -103,7 +103,7 @@ else
                             <InputNumber class="form-control" @bind-Value="ItemModel.PriceAmount" />
                         </div>
                         <div class="col-md-2">
-                            <label class="form-label">Currency</label>
+                            <label class="form-label">Currency symbol</label>
                             <InputText class="form-control" @bind-Value="ItemModel.CurrencyCode" />
                         </div>
                         <div class="col-md-2">
@@ -304,7 +304,7 @@ else
                             <InputDate class="form-control" @bind-Value="SettingsModel.BirthDate" />
                         </div>
                         <div class="col-md-2">
-                            <label class="form-label">Currency</label>
+                            <label class="form-label">Currency symbol</label>
                             <InputText class="form-control" @bind-Value="SettingsModel.CurrencyCode" />
                         </div>
                         <div class="col-md-3">

src/BirthList.Web/Components/Pages/RegistryContributionAmount.razor

@@ -21,11 +21,11 @@ else
         <div class="card p-3">
             @if (RepresentableAmounts.Count == 0)
             {
-                <p class="text-muted mb-0">No representable amount can be formed from configured QR codes up to €200.</p>
+                <p class="text-muted mb-0">No representable amount can be formed from configured QR codes up to @GetCurrencySymbol()200.</p>
             }
             else
             {
-                <label class="form-label">Select amount: €@SelectedAmount</label>
+                <label class="form-label">Select amount: @GetCurrencySymbol()@SelectedAmount</label>
                 <input type="range"
                        class="form-range"
                        min="0"
@@ -45,7 +45,7 @@ else
                 <ul class="mb-3">
                     @foreach (var suggestion in Suggestions)
                     {
-                        <li>@suggestion.RepeatCount x €@suggestion.Amount</li>
+                        <li>@suggestion.RepeatCount x @GetCurrencySymbol()@suggestion.Amount</li>
                     }
                 </ul>
 
@@ -55,7 +55,7 @@ else
                         @for (var i = 0; i < suggestion.RepeatCount; i++)
                         {
                             <div>
-                                <div class="small mb-1">€@suggestion.Amount</div>
+                                <div class="small mb-1">@GetCurrencySymbol()@suggestion.Amount</div>
                                 <img src="@BuildQrImageUrl(suggestion.QrCodeUrl)" alt="QR code @suggestion.Amount" class="img-fluid" style="max-height: 220px;" />
                                 <div class="small text-muted text-break">
                                     <a href="@suggestion.QrCodeUrl" target="_blank" rel="noopener noreferrer">Open payment link</a>

src/BirthList.Web/Components/Pages/RegistryContributionAmount.razor.cs

@@ -207,4 +207,11 @@ public partial class RegistryContributionAmount : ComponentBase
         public string QrCodeUrl { get; init; } = string.Empty;
         public int RepeatCount { get; init; }
     }
+
+    protected string GetCurrencySymbol()
+    {
+        return string.IsNullOrWhiteSpace(Registry?.CurrencyCode)
+            ? "€"
+            : Registry.CurrencyCode;
+    }
 }

src/BirthList.Web/Components/Pages/RegistryPublic.razor

@@ -87,7 +87,18 @@ else
                                         }
                                         @if (item.ParticipationAllowed && GetParticipationTotalAmount(item).HasValue)
                                         {
-                                            <p class="mb-2"><strong>Participation:</strong> €@item.MoneyFulfilledAmount.ToString("0.00") out of €@GetParticipationTotalAmount(item)!.Value.ToString("0.00") fulfilled</p>
+                                            <p class="mb-2">
+                                                <strong>Participation:</strong>
+                                                @item.CurrencyCode@item.MoneyFulfilledAmount.ToString("0.00")
+                                                @if (GetParticipationTotalAmount(item)!.Value > 0)
+                                                {
+                                                    <span> out of @item.CurrencyCode@GetParticipationTotalAmount(item)!.Value.ToString("0.00") fulfilled</span>
+                                                }
+                                                else
+                                                {
+                                                    <span> fulfilled</span>
+                                                }
+                                            </p>
                                         }
 
                                         @if (item.Purchasers.Count > 0 || item.Contributors.Count > 0)