Add dismissible pending updates alert banner at top of Dashboard

Shows a warning-colored banner when sources need updating, with an X to dismiss.
The existing Pending Updates section lower in the dashboard remains unchanged.

Fixes #18

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

PortfolioJournal/Views/Dashboard/DashboardView.swift

@@ -11,6 +11,7 @@ struct DashboardView: View {
     @State private var showingCustomize = false
     @State private var sectionConfigs = DashboardLayoutStore.load()
     @AppStorage("calmModeEnabled") private var calmModeEnabled = true
+    @State private var pendingAlertDismissed = false
 
     init() {
         _viewModel = StateObject(wrappedValue: DashboardViewModel())
@@ -24,6 +25,18 @@ struct DashboardView: View {
                 ScrollView {
                     VStack(spacing: 20) {
                         if viewModel.hasData {
+                            if !pendingAlertDismissed && !viewModel.sourcesNeedingUpdate.isEmpty {
+                                PendingUpdatesAlertBanner(
+                                    count: viewModel.sourcesNeedingUpdate.count,
+                                    onDismiss: {
+                                        withAnimation {
+                                            pendingAlertDismissed = true
+                                        }
+                                    }
+                                )
+                                .transition(.move(edge: .top).combined(with: .opacity))
+                            }
+
                             ForEach(visibleSections) { config in
                                 sectionView(for: config)
                             }
@@ -1046,6 +1059,36 @@ struct EmptyDashboardView: View {
     }
 }
 
+// MARK: - Pending Updates Alert Banner
+
+struct PendingUpdatesAlertBanner: View {
+    let count: Int
+    let onDismiss: () -> Void
+
+    var body: some View {
+        HStack(spacing: 10) {
+            Image(systemName: "exclamationmark.triangle.fill")
+                .foregroundColor(.white)
+
+            Text("\(count) source\(count == 1 ? "" : "s") pending update")
+                .font(.subheadline.weight(.semibold))
+                .foregroundColor(.white)
+
+            Spacer()
+
+            Button(action: onDismiss) {
+                Image(systemName: "xmark")
+                    .font(.caption.weight(.bold))
+                    .foregroundColor(.white.opacity(0.8))
+            }
+        }
+        .padding(.horizontal, 16)
+        .padding(.vertical, 12)
+        .background(Color.appWarning)
+        .cornerRadius(AppConstants.UI.cornerRadius)
+    }
+}
+
 // MARK: - Pending Updates Card
 
 struct PendingUpdatesCard: View {