PR U-1: AccountSelector reacts to Accounts arriving late

Move the SelectedAccount = Accounts.FirstOrDefault(...) lookup from
OnInitialized to OnParametersSet so the preselection tracks the
Accounts list arriving asynchronously (every caller now passes []
first and hydrates after an await). Idempotent — the OnSelectedChanged
callback path returns the same AccountId back and the parent re-render
lookup finds the same account.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Schaad.Accounting.UI/Components/Pages/Controls/AccountSelector.razor.cs

@@ -14,7 +14,11 @@ public partial class AccountSelector : ComponentBase
     
     private Account? SelectedAccount { get; set; }
 
-    protected override void OnInitialized()
+    // OnParametersSet, not OnInitialized: OnInitialized fires once, but callers now
+    // pass an empty Accounts list on first render and hydrate it after an await.
+    // OnParametersSet re-runs the lookup whenever Accounts or AccountId change, so the
+    // preselection tracks late-arriving data.
+    protected override void OnParametersSet()
     {
         SelectedAccount = Accounts.FirstOrDefault(account => account.Id == AccountId);
     }