many fixes and improvements - rework for modules/ and common/

feat(emailer): add Postmark and Resend providers

backend/Modules/Tipping/Data/TippingDbContext.cs

@@ -0,0 +1,22 @@
+namespace Hutopy.Modules.Tipping.Data;
+
+public sealed class TippingDbContext(
+    DbContextOptions<TippingDbContext> options)
+    : DbContext(options)
+{
+    public const string SchemaName = "Tipping";
+
+    public DbSet<Tip> Tips => Set<Tip>();
+    
+    
+    protected override void OnModelCreating(ModelBuilder modelBuilder)
+    {
+        modelBuilder.HasDefaultSchema(SchemaName);
+
+        modelBuilder
+            .Entity<Tip>()
+            .Property(c => c.CreatedAt)
+            .ValueGeneratedOnAdd()
+            .HasDefaultValueSql("CURRENT_TIMESTAMP");
+    }
+}