feat(accessibility): add native keyboard dialogs and semantic account links (U08)

src/Duempelkas.App/Components/Dialogs/AddTransferDialog.razor

@@ -2,8 +2,7 @@
 @inject IEntryService EntryService
 @inject IAccountService AccountService
 
-<div class="dialog-backdrop">
-    <div class="dialog-content booking-dialog" @onclick:stopPropagation="true">
+<ModalDialog @ref="modal" Title="Geld zwischen Konten verschieben" OnCancel="OnCancel" Busy="isSaving" Dirty="@(committedResult == null && IsDirty)">
         <h5 class="mb-3">@(EditEntry != null ? "Umbuchung bearbeiten" : "Neue Umbuchung")</h5>
 
         <p class="text-muted">Erfasst nur die Buchung. Führt keine Banküberweisung aus.</p>
@@ -11,7 +10,7 @@
         <form @onsubmit="Save" @onsubmit:preventDefault="true" aria-busy="@(isSaving ? "true" : "false")">
             <fieldset disabled="@(isSaving || committedResult != null || completed)">
                 <div class="form-container">
-                    <label class="form-label">Zielkonto</label>
+                    <label class="form-label" for="transfer-account">Zielkonto</label>
                     <select id="transfer-account" class="form-select" @bind="targetAccountId">
                         <option value="0">— Auswählen —</option>
                         @foreach (var acc in accounts.Where(a => a.Id != SourceAccountId))
@@ -20,13 +19,13 @@
                         }
                     </select>
 
-                    <label class="form-label">Datum</label>
+                    <label class="form-label" for="transfer-date">Datum</label>
                     <input id="transfer-date" type="date" class="form-control" value="@dateText" @oninput="e => dateText = e.Value?.ToString() ?? string.Empty" />
 
-                    <label class="form-label">Bezeichnung</label>
+                    <label class="form-label" for="transfer-title">Bezeichnung</label>
                     <input id="transfer-title" type="text" class="form-control" @bind="title" @bind:event="oninput" placeholder="Beschreibung der Umbuchung" />
 
-                    <label class="form-label">Betrag (€)</label>
+                    <label class="form-label" for="transfer-amount">Betrag (€)</label>
                     <div><AmountInput Id="transfer-amount" @bind-Value="amountText" />
                         <p class="text-muted">Betrag ohne Minuszeichen.</p></div>
                 </div>
@@ -47,6 +46,6 @@
                 <button type="button" class="btn btn-outline-secondary" disabled="@isSaving" @onclick="Cancel"><i class="bi bi-x-lg"></i> Abbrechen</button>
             </div>
         </form>
-    </div>
-</div>
+</ModalDialog>
 
+@code { private ModalDialog? modal; }