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/Components/Layout/NavMenu.razor

@@ -0,0 +1,14 @@
+<MudNavMenu>
+    <MudNavLink Href="/" Match="NavLinkMatch.All" Icon="@Icons.Material.Filled.Dashboard">
+        Dashboard
+    </MudNavLink>
+    <MudNavLink Href="/standorte" Match="NavLinkMatch.Prefix" Icon="@Icons.Material.Filled.LocationOn">
+        Standorte
+    </MudNavLink>
+    <MudNavLink Href="/settings" Match="NavLinkMatch.Prefix" Icon="@Icons.Material.Filled.Settings">
+        Settings
+    </MudNavLink>
+    <MudNavLink Href="/logs" Match="NavLinkMatch.Prefix" Icon="@Icons.Material.Filled.List">
+        Logs
+    </MudNavLink>
+</MudNavMenu>