feat: add Migrator console project

- Dedicated HrynCo.NotificationService.Migrator console app
- Reads App:ConnectionString from config/env
- Calls db.Database.MigrateAsync() with clear log output
- Own Dockerfile (runtime:10.0 base, no SDK overhead)
- Replaces SDK volume-mount approach in docker-compose
- Added to solution with /docker/Migrator/ folder

Ref: IT-628

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

HrynCo.NotificationService.Migrator/HrynCo.NotificationService.Migrator.csproj

@@ -0,0 +1,25 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net10.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.EntityFrameworkCore.Design">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+    <PackageReference Include="Microsoft.Extensions.Hosting" />
+    <PackageReference Include="Serilog.Extensions.Hosting" />
+    <PackageReference Include="Serilog.Settings.Configuration" />
+    <PackageReference Include="Serilog.Sinks.Console" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\HrynCo.NotificationService.DAL.EF\HrynCo.NotificationService.DAL.EF.csproj" />
+  </ItemGroup>
+
+</Project>