Add PartnerDepot and EkaerHistory entities, update tags

- Introduced PartnerDepot and EkaerHistory entity classes with serialization and DB mapping.
- Made ICompanyInfoBase.TaxId nullable.
- Added new DB table name constants for PartnerDepot and EkaerHistory.
- Added SignalR tag constants for PartnerDepot and EkaerHistory operations.
- Updated SQL schema compare connection strings and item order.

AyCode.Core/Interfaces/ICompanyInfoBase.cs

@@ -9,7 +9,7 @@ namespace AyCode.Core.Interfaces;
 public interface ICompanyInfoBase
 {
     string Name { get; }
-    string TaxId { get; }
+    string? TaxId { get; }
     string CountryCode { get; }
     string PostalCode { get; }
     string City { get; }