Add push notifications (Pushe) + Capacitor shell for Koja

Iran-safe push for the Koja Android app (Cafe Bazaar / Myket / direct APK):

Backend
- PushDevice entity + EF migration; idempotent device register/unregister.
- IPushSender / PusheNotificationSender (Pushe REST) — SendToTopic for
  marketing (city-{slug}) and saved-café (cafe-{slug}) pushes, SendToTokens
  for targeted order/reservation updates.
- Public register/unregister endpoints + authorized topic broadcast.

App
- capacitor.config.ts (native WebView loads the live PWA via server.url).
- push.ts Pushe glue: topic helpers + backend device registration.

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

src/Meezi.Core/Interfaces/IPushSender.cs

@@ -0,0 +1,32 @@
+namespace Meezi.Core.Interfaces;
+
+/// <summary>
+/// Sends push notifications through the Pushe gateway (Iran-safe; FCM is
+/// unreliable inside Iran). Topics are subscribed client-side via the native
+/// Pushe SDK; this service triggers the actual sends from the backend.
+/// </summary>
+public interface IPushSender
+{
+    /// <summary>
+    /// Broadcasts to every device subscribed to a Pushe topic.
+    /// Topics: <c>city-{slug}</c> (marketing / new cafés),
+    /// <c>cafe-{slug}</c> (saved-café alerts).
+    /// </summary>
+    Task SendToTopicAsync(
+        string topic,
+        string title,
+        string body,
+        string? deepLink = null,
+        CancellationToken cancellationToken = default);
+
+    /// <summary>
+    /// Sends to one or more specific device tokens — used for transactional
+    /// order / reservation updates.
+    /// </summary>
+    Task SendToTokensAsync(
+        IReadOnlyCollection<string> tokens,
+        string title,
+        string body,
+        string? deepLink = null,
+        CancellationToken cancellationToken = default);
+}