refactor: replace internal UnitOfWork with NotificationUnitOfWork and NotificationBaseRepository

- Consolidate unit of work implementation with NotificationUnitOfWork.
- Refactor repositories to use NotificationBaseRepository for consistency.
- Simplify request handlers by removing IUnitOfWork dependency.
- Update related tests and service registration.

HrynCo.NotificationService.DAL.Abstract/HrynCo.NotificationService.DAL.Abstract.csproj

@@ -1,13 +1,13 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
-  <ItemGroup>
-    <PackageReference Include="HrynCo.DAL.Abstract" />
-  </ItemGroup>
-
   <PropertyGroup>
     <TargetFramework>net10.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
   </PropertyGroup>
 
+  <ItemGroup>
+    <PackageReference Include="HrynCo.DAL.Abstract" />
+  </ItemGroup>
+
 </Project>

HrynCo.NotificationService.DAL.Abstract/Providers/EmailChannel.cs

@@ -12,4 +12,4 @@ public class EmailChannel : Entity
     public int? MonthlyLimit { get; set; }
     public int WarnThresholdPercent { get; set; } = 90;
     public bool IsActive { get; set; } = true;
-}
+}

HrynCo.NotificationService.DAL.Abstract/Providers/EmailChannelUsage.cs

@@ -1,13 +1,14 @@
-using HrynCo.DAL.Abstract.Entities;
-
 namespace HrynCo.NotificationService.DAL.Abstract.Providers;
 
 /// <summary>
 /// Tracks email send counts per EmailChannel per calendar day.
 /// Monthly counts are derived by summing daily records within a month.
 /// </summary>
-public class EmailChannelUsage : Entity
+public class EmailChannelUsage
 {
+    public Guid Id { get; set; }
+    public DateTimeOffset Created { get; set; }
+    public DateTimeOffset? Updated { get; set; }
     public Guid ProviderId { get; set; }
     public DateOnly Date { get; set; }
     public int SentCount { get; set; }