Ensure uninherited types are sealed

Resolved mediator source geenrator conflict with tests

LiteCharms.Features/Postgres/DataProtectionDbContext.cs

@@ -1,6 +1,6 @@
 namespace LiteCharms.Features.Postgres;
 
-public class DataProtectionDbContext(DbContextOptions<DataProtectionDbContext> options) : DbContext(options), IDataProtectionKeyContext
+public sealed class DataProtectionDbContext(DbContextOptions<DataProtectionDbContext> options) : DbContext(options), IDataProtectionKeyContext
 {
     public DbSet<DataProtectionKey> DataProtectionKeys { get; set; }
 

LiteCharms.Features/Postgres/DataProtectionDbContextFactory.cs

@@ -2,7 +2,7 @@
 
 namespace LiteCharms.Features.Postgres;
 
-public class DataProtectionDbContextFactory : IDesignTimeDbContextFactory<DataProtectionDbContext>
+public sealed class DataProtectionDbContextFactory : IDesignTimeDbContextFactory<DataProtectionDbContext>
 {
     public DataProtectionDbContext CreateDbContext(string[] args)
     {

LiteCharms.Features/Postgres/Migrations/20260614075149_Init.cs

@@ -6,7 +6,7 @@ using Npgsql.EntityFrameworkCore.PostgreSQL.Metadata;
 namespace LiteCharms.Features.Postgres.Migrations
 {
     /// <inheritdoc />
-    public partial class Init : Migration
+    public sealed partial class Init : Migration
     {
         /// <inheritdoc />
         protected override void Up(MigrationBuilder migrationBuilder)