Add password changing

Hcs.WebApp/Services/IdentityService.cs

@@ -0,0 +1,25 @@
+using Microsoft.AspNetCore.Components;
+
+namespace Hcs.WebApp.Services
+{
+    public class IdentityService(NavigationManager navigationManager, IHttpClientFactory factory)
+    {
+        private readonly Uri baseUri = new($"{navigationManager.BaseUri}identity/");
+        private readonly HttpClient httpClient = factory.CreateClient("WithIdentity");
+
+        public async Task ChangePassword(string oldPassword, string newPassword)
+        {
+            var uri = new Uri($"{baseUri}change-password");
+            var content = new FormUrlEncodedContent(new Dictionary<string, string> {
+                { "oldPassword", oldPassword },
+                { "newPassword", newPassword }
+            });
+            var response = await httpClient.PostAsync(uri, content);
+            if (!response.IsSuccessStatusCode)
+            {
+                var message = await response.Content.ReadAsStringAsync();
+                throw new ApplicationException(message);
+            }
+        }
+    }
+}