feat(i18n): persist Bokmal preference globally

JobTrackerApi.Tests/AuthAndSystemControllerTests.cs

@@ -426,6 +426,35 @@ public sealed class AuthAndSystemControllerTests
         Assert.Equal("Ada L.", user.DisplayName);
     }
 
+    [Fact]
+    public async Task Language_preference_normalizes_and_persists_norwegian_bokmal()
+    {
+        var user = new ApplicationUser { Id = "user-1", UiLanguage = "en" };
+        var users = CreateUserManager();
+        users.Setup(x => x.GetUserAsync(It.IsAny<System.Security.Claims.ClaimsPrincipal>())).ReturnsAsync(user);
+        users.Setup(x => x.UpdateAsync(user)).ReturnsAsync(IdentityResult.Success);
+        var controller = new AuthController(BuildConfig(), users.Object, Mock.Of<ITokenService>(), Mock.Of<IAppEmailSender>(), Mock.Of<IGoogleTokenValidator>(), Mock.Of<IMicrosoftTokenValidator>(), NullLogger<AuthController>.Instance, Mock.Of<ITwoFactorPendingTokenService>(), TestHostFactory.CreateInMemoryDb());
+
+        var result = await controller.UpdateLanguagePreference(new AuthController.UpdateLanguagePreferenceRequest("nb"));
+
+        Assert.IsType<NoContentResult>(result);
+        Assert.Equal("nb-NO", user.UiLanguage);
+    }
+
+    [Fact]
+    public async Task Language_preference_rejects_an_unsupported_locale()
+    {
+        var user = new ApplicationUser { Id = "user-1", UiLanguage = "en" };
+        var users = CreateUserManager();
+        users.Setup(x => x.GetUserAsync(It.IsAny<System.Security.Claims.ClaimsPrincipal>())).ReturnsAsync(user);
+        var controller = new AuthController(BuildConfig(), users.Object, Mock.Of<ITokenService>(), Mock.Of<IAppEmailSender>(), Mock.Of<IGoogleTokenValidator>(), Mock.Of<IMicrosoftTokenValidator>(), NullLogger<AuthController>.Instance, Mock.Of<ITwoFactorPendingTokenService>(), TestHostFactory.CreateInMemoryDb());
+
+        var result = await controller.UpdateLanguagePreference(new AuthController.UpdateLanguagePreferenceRequest("sv-SE"));
+
+        Assert.IsType<BadRequestObjectResult>(result);
+        users.Verify(x => x.UpdateAsync(It.IsAny<ApplicationUser>()), Times.Never);
+    }
+
     [Fact]
     public async Task Request_email_change_keeps_current_email_and_sends_confirmation_to_new_address()
     {

JobTrackerApi.Tests/MigrationChainTests.cs

@@ -40,6 +40,9 @@ public sealed class MigrationChainTests
             SELECT COUNT(*) FROM pragma_table_info('AspNetUsers')
             WHERE name = 'EmailFollowUpRemindersEnabled' AND dflt_value IN ('1', 'true');
             """));
+        Assert.Equal(1, await ScalarAsync<long>(connection, """
+            SELECT COUNT(*) FROM pragma_table_info('AspNetUsers') WHERE name = 'UiLanguage';
+            """));
     }
 
     [Fact]
@@ -93,6 +96,7 @@ public sealed class MigrationChainTests
         Assert.Contains("CONSTRAINT `FK_AccountDeletionFiles_Request`", script, StringComparison.Ordinal);
         Assert.Contains("CREATE TABLE IF NOT EXISTS `AspNetUsers`", script, StringComparison.Ordinal);
         Assert.Contains("CREATE TABLE IF NOT EXISTS `AiInteractions`", script, StringComparison.Ordinal);
+        Assert.Contains("`UiLanguage` varchar(16)", script, StringComparison.Ordinal);
         Assert.All(
             Regex.Matches(script, "CONSTRAINT `([^`]+)`").Select(match => match.Groups[1].Value),
             identifier => Assert.True(identifier.Length <= 64, $"MariaDB constraint identifier exceeds 64 characters: {identifier}"));