feat(templates): add localized push templates and actions

Share template keys across email and push with independent editors and revisions. Render localized actions and preserve version-one delivery.

Ref: IT-1627

HrynCo.NotificationService.Web.IntegrationTests/AdminDeletionTests.cs

@@ -102,7 +102,7 @@ public sealed class AdminDeletionTests(TemplateDatabaseFixture fixture) : IClass
         await using var context = await DefinitionApiTestContext.CreateAsync(fixture);
         var root = $"/admin/services/{context.ServiceId}";
         var templates = await context.Client.GetStringAsync(root);
-        Assert.Contains("No email templates for this service yet.", templates);
+        Assert.Contains("No templates for this service yet.", templates);
         Assert.Contains("Create First Template", templates);
         Assert.Contains(root + "/templates/create", templates);
         Assert.Contains("template-key-filter", templates);
@@ -129,7 +129,7 @@ public sealed class AdminDeletionTests(TemplateDatabaseFixture fixture) : IClass
         Assert.Contains("Could not load templates", html);
         Assert.Contains("Templates are unavailable", html);
         Assert.DoesNotContain("Create First Template", html);
-        Assert.DoesNotContain("No email templates for this service yet.", html);
+        Assert.DoesNotContain("No templates for this service yet.", html);
     }
 
     private static void AssertConfirmationReset(string html) =>