Convert TrafagSalesExporter from console app to Blazor Server app with MudBlazor UI

- Replaced console app with .NET 8 Blazor Server architecture
- Added EF Core SQLite database (trafag_exporter.db) with auto-seed data
- Models: HanaServer, Site, SharePointConfig, ExportSettings, ExportLog, SalesRecord
- Services: HanaQueryService (with configurable dateFilter), ExcelExportService,
  SharePointUploadService, ExportOrchestrationService (with live status events),
  TimerBackgroundService (scheduled daily export)
- MudBlazor UI pages: Dashboard (export status + manual trigger), Standorte
  (HANA server + site CRUD), Settings (SharePoint + timer config), Logs (filtered view)
- SAP HANA queries unchanged (INV + CRN with exact SAP B1 table joins)
- SharePoint upload via Microsoft Graph with app registration auth

https://claude.ai/code/session_012heAXNMbbyxqYf2S2HrKLj

TrafagSalesExporter/Models/SharePointConfig.cs

@@ -0,0 +1,11 @@
+namespace TrafagSalesExporter.Models;
+
+public class SharePointConfig
+{
+    public int Id { get; set; }
+    public string SiteUrl { get; set; } = string.Empty;
+    public string ExportFolder { get; set; } = string.Empty;
+    public string TenantId { get; set; } = string.Empty;
+    public string ClientId { get; set; } = string.Empty;
+    public string ClientSecret { get; set; } = string.Empty;
+}