fix(postgres): map DateTime to timestamp without time zone (Npgsql rejects Kind=Unspecified on timestamptz)

src/GreenHome.Infrastructure/Data/GreenHomeDbContext.cs

@@ -38,6 +38,21 @@ public sealed class GreenHomeDbContext : DbContext
     {
         base.OnModelCreating(modelBuilder);
 
+        // Postgres: map DateTime -> "timestamp without time zone" (not timestamptz).
+        // Mirrors SQL Server's naive datetime2 — accepts any DateTime.Kind, so values
+        // copied from SQL Server (Kind=Unspecified) or written by the API won't crash.
+        if (Database.ProviderName == "Npgsql.EntityFrameworkCore.PostgreSQL")
+        {
+            foreach (var et in modelBuilder.Model.GetEntityTypes())
+            {
+                foreach (var p in et.GetProperties())
+                {
+                    if (p.ClrType == typeof(DateTime) || p.ClrType == typeof(DateTime?))
+                        p.SetColumnType("timestamp");
+                }
+            }
+        }
+
         modelBuilder.Entity<Domain.Device>(b =>
         {
             b.ToTable("Devices");