Implement template export/import endpoints and enhance grid generation logic

Added new endpoints for exporting and importing grid configurations in TemplateEndpoints, allowing for better management of template data. Enhanced the GenerateGridCommandHandler to support seasonal layers in grid generation, improving scheduling accuracy during holiday periods. Updated related classes and records to accommodate these changes, ensuring a cohesive integration of new features. Improved documentation for clarity and maintainability.

backend/tests/TeleWave.Application.Tests/Programming/GridPlanPreviewTests.cs

@@ -116,7 +116,10 @@ public class GridPlanPreviewTests
 
         await using var db = fixture.New();
         var result = await new PreviewGeneratedGridQueryHandler(
-            new GridPlanner(db, GroupServices.Dynamic(db), new GroupElementResolver(db))
+            new GridPlanner(
+                db,
+                new GroupCatalog(db, GroupServices.Dynamic(db), new GroupElementResolver(db))
+            )
         ).Handle(
             new PreviewGeneratedGridQuery(
                 channelId,
@@ -143,7 +146,10 @@ public class GridPlanPreviewTests
         await using var db = fixture.New();
 
         var result = await new PreviewGeneratedGridQueryHandler(
-            new GridPlanner(db, GroupServices.Dynamic(db), new GroupElementResolver(db))
+            new GridPlanner(
+                db,
+                new GroupCatalog(db, GroupServices.Dynamic(db), new GroupElementResolver(db))
+            )
         ).Handle(
             new PreviewGeneratedGridQuery(
                 Guid.NewGuid(),