feat: 添加推送通知功能，支持订阅和发送通知

WebApi/Controllers/NotificationController.cs

@@ -0,0 +1,27 @@
+namespace WebApi.Controllers;
+
+[ApiController]
+[Route("api/[controller]")]
+public class NotificationController(INotificationService notificationService) : ControllerBase
+{
+    [HttpGet("vapid-public-key")]
+    public async Task<IActionResult> GetVapidPublicKey()
+    {
+        var key = await notificationService.GetVapidPublicKeyAsync();
+        return Ok(new { publicKey = key });
+    }
+
+    [HttpPost("subscribe")]
+    public async Task<IActionResult> Subscribe([FromBody] PushSubscriptionEntity subscription)
+    {
+        await notificationService.SubscribeAsync(subscription);
+        return Ok();
+    }
+    
+    [HttpPost("test")]
+    public async Task<IActionResult> TestNotification([FromQuery] string message)
+    {
+        await notificationService.SendNotificationAsync(message);
+        return Ok();
+    }
+}