- Switch to custom edit model (MassDataEditModel) for popup editing, enabling granular field validation and UI control
- Replace default editors with explicit DxTextBox/DxCheckBox bindings
- Add AmountText field for string input and validation; validate and convert in OnEditModelSaving
- Implement duplicate customer check via new GetByCustomerNameAsync API method
- Show ValidationSummary in popup; manage validation state with ValidationMessageStore and EditContext
- Make popup header and width dynamic; show procedure ComboBox only for existing records
- Restore "New" button in grid command column
- Refactor CatalogsGrid to handle validation clearing in OnEditFieldChanged instead of OnTitleChanged
- General improvements to real-time validation feedback
Introduces MassData management to backend and Blazor frontend:
- Adds API endpoint for MassData count and paging
- Updates repository and controller for count support
- Implements MediatR query/handler for count
- Adds Blazor page and grid for viewing/editing MassData
- Registers MassDataApiClient and integrates with DI
- Supports paging, upsert, and UI feedback in grid
