Add native iOS notifications (#64)

ios/Sources/HomeScreen.swift

@@ -104,12 +104,23 @@ final class HomeViewController: RefreshingTableViewController {
                 finishPagination(hasMore: result.nextPage != nil)
                 title = page?.serverName
                 if requestedPage == 1 { tableView.tableHeaderView = page.map { page in
-                    HeatmapView(page: page, selectedFilter: filter.rawValue) { [weak self] index in
+                    HeatmapView(
+                        page: page,
+                        selectedFilter: filter.rawValue,
+                        onFilter: { [weak self] index in
                         guard let self, let filter = ActivityFilter(rawValue: index) else { return }
                         guard filter != self.filter else { return }
                         self.filter = filter
                         self.loadPage(1, refreshing: false)
-                    }
+                        },
+                        onNotifications: { [weak self] in
+                            guard let self else { return }
+                            self.navigationController?.pushViewController(
+                                NotificationsViewController(context: self.context),
+                                animated: true
+                            )
+                        }
+                    )
                 } }
                 updateActivities()
             } catch {
@@ -179,7 +190,12 @@ final class HeatmapView: UIView {
     private let cells: [HeatCell]
     private let calendar = Calendar(identifier: .gregorian)
 
-    init(page: HomePage, selectedFilter: Int, onFilter: @escaping (Int) -> Void) {
+    init(
+        page: HomePage,
+        selectedFilter: Int,
+        onFilter: @escaping (Int) -> Void,
+        onNotifications: @escaping () -> Void
+    ) {
         cells = page.heatCells
         super.init(frame: CGRect(x: 0, y: 0, width: 0, height: 180))
         backgroundColor = .systemBackground
@@ -225,6 +241,15 @@ final class HeatmapView: UIView {
             button.widthAnchor.constraint(equalToConstant: 44).isActive = true
             filters.addArrangedSubview(button)
         }
+        let notifications = UIButton(
+            type: .custom,
+            primaryAction: UIAction { _ in onNotifications() }
+        )
+        notifications.setImage(UIImage(systemName: "bell"), for: .normal)
+        notifications.tintColor = .secondaryLabel
+        notifications.accessibilityLabel = "Notifications"
+        notifications.widthAnchor.constraint(equalToConstant: 44).isActive = true
+        filters.addArrangedSubview(notifications)
         addSubview(filters)
         NSLayoutConstraint.activate([
             filters.centerXAnchor.constraint(equalTo: centerXAnchor),