feat(data): rename *.Services projects, lift TrackEntity onto BlazorBlocks data layer, regenerate initial Postgres migration

DeepDrftWeb.Services → DeepDrftData; DeepDrftContent.Services → DeepDrftContent.Data.
TrackEntity:BaseEntity, TrackRepository:Repository<>, TrackManager:Manager<>+ITrackService.
Drops DeepDrftModels PagingParameters/PagedResult in favour of Models.Common.* from BlazorBlocks.
InitialCreate migration captures full schema including is_deleted index.

NuGet.Config

@@ -4,5 +4,6 @@
     <add key="nuget.org" value="https://api.nuget.org/v3/index.json" />
     <!-- Machine-specific local feed — update path if not at C:\Development\AuthBlocks\nupkgs\ -->
     <add key="AuthBlocks-local" value="C:\Development\AuthBlocks\nupkgs\" />
+    <add key="BlazorBlocks-local" value="C:\Development\BlazorBlocks\nupkgs\" />
   </packageSources>
 </configuration>