feat(android): implement snackbar overlay behavior

pedi-foods/Sources/PediFoods/Components/SnackbarOverlay.swift

@@ -3,13 +3,51 @@ import SwiftUI
 struct SnackbarOverlay: View {
 #if os(Android)
     let center: SnackbarCenter
+    @State var current: SnackbarMessage?
+    @State var observer: Any?
 #else
     @ObservedObject var center: SnackbarCenter
 #endif
 
     var body: some View {
 #if os(Android)
-        EmptyView()
+        VStack {
+            if let message = current {
+                HStack(spacing: 10) {
+                    if let icon = message.iconSystemName, !icon.isEmpty {
+                        Image(systemName: icon)
+                            .font(.system(size: 16, weight: .semibold))
+                    }
+                    Text(message.title)
+                        .font(AppTypography.heading3)
+                        .multilineTextAlignment(.leading)
+                        .lineLimit(3)
+                    Spacer(minLength: 0)
+                }
+                .foregroundStyle(Color.white)
+                .padding(.top, 14)
+                .padding(.horizontal, 16)
+                .padding(.bottom, 16)
+                .frame(maxWidth: .infinity, alignment: .leading)
+                .background(message.style.backgroundColor)
+                .appContentShape(Rectangle())
+                .onTapGesture {
+                    center.handleTap()
+                }
+                .transition(.move(edge: .top).combined(with: .opacity))
+                .zIndex(999)
+            }
+            Spacer()
+        }
+        .animation(.spring(response: 0.3, dampingFraction: 0.9), value: current?.id)
+        .allowsHitTesting(current != nil)
+        .onAppear {
+            current = center.current
+            attachObserverIfNeeded()
+        }
+        .onDisappear {
+            detachObserver()
+        }
 #else
         VStack {
             if let message = center.current {
@@ -43,4 +81,25 @@ struct SnackbarOverlay: View {
         .allowsHitTesting(center.current != nil)
 #endif
     }
+
+#if os(Android)
+    private func attachObserverIfNeeded() {
+        guard observer == nil else { return }
+        observer = NotificationCenter.default.addObserver(
+            forName: .snackbarDidChange,
+            object: nil,
+            queue: nil
+        ) { _ in
+            Task { @MainActor in
+                current = center.current
+            }
+        }
+    }
+
+    private func detachObserver() {
+        guard let observer else { return }
+        NotificationCenter.default.removeObserver(observer)
+        self.observer = nil
+    }
+#endif
 }

pedi-foods/Sources/PediFoods/State/SnackbarCenter.swift

@@ -1,11 +1,16 @@
 import Foundation
 import SwiftUI
 
+extension Notification.Name {
+    static let snackbarDidChange = Notification.Name("snackbarDidChange")
+}
+
 #if os(Android)
 @MainActor
 final class SnackbarCenter {
     static let shared = SnackbarCenter()
     var current: SnackbarMessage?
+    private var dismissTask: Task<Void, Never>?
 
     func show(
         title: String,
@@ -14,11 +19,40 @@ final class SnackbarCenter {
         duration: TimeInterval = 3.5,
         action: (() -> Void)? = nil
     ) {
+        dismissTask?.cancel()
+        current = SnackbarMessage(
+            title: title,
+            style: style,
+            iconSystemName: icon,
+            duration: duration,
+            action: action
+        )
+        notifyChange()
+
+        dismissTask = Task { [weak self] in
+            let nanos = UInt64(max(0.2, duration) * 1_000_000_000)
+            try? await Task.sleep(nanoseconds: nanos)
+            guard !Task.isCancelled else { return }
+            self?.dismiss(animated: true)
+        }
+    }
+
+    func handleTap() {
+        let action = current?.action
+        dismiss(animated: true)
         action?()
     }
 
-    func handleTap() {}
-    func dismiss(animated: Bool) {}
+    func dismiss(animated: Bool) {
+        dismissTask?.cancel()
+        dismissTask = nil
+        current = nil
+        notifyChange()
+    }
+
+    private func notifyChange() {
+        NotificationCenter.default.post(name: .snackbarDidChange, object: nil)
+    }
 }
 #else
 @MainActor