Add MassData API with CQRS, repository, and DbContext

Introduce MassData feature with new API endpoints for querying and upserting records by customer name. Add DTOs, AutoMapper profile, MediatR CQRS handlers, repository pattern, and MassDataDbContext. Register new services in DI and add MassDataConnection to configuration. Upsert uses stored procedure. Enables full CRUD for Massdata via dedicated API.

DbFirst.Infrastructure/MassDataDbContext.cs

@@ -0,0 +1,44 @@
+using DbFirst.Domain.Entities;
+using Microsoft.EntityFrameworkCore;
+
+namespace DbFirst.Infrastructure;
+
+public class MassDataDbContext : DbContext
+{
+    public MassDataDbContext(DbContextOptions<MassDataDbContext> options)
+        : base(options)
+    {
+    }
+
+    public virtual DbSet<Massdata> Massdata { get; set; }
+
+    protected override void OnModelCreating(ModelBuilder modelBuilder)
+    {
+        modelBuilder.Entity<Massdata>(entity =>
+        {
+            entity.HasKey(e => e.Id);
+            entity.ToTable("MASSDATA");
+
+            entity.Property(e => e.Id).HasColumnName("ID");
+            entity.Property(e => e.CustomerName)
+                .HasMaxLength(200)
+                .IsUnicode(false)
+                .HasColumnName("CustomerName");
+            entity.Property(e => e.Amount)
+                .HasColumnType("decimal(12,2)")
+                .HasColumnName("Amount");
+            entity.Property(e => e.Category)
+                .HasMaxLength(100)
+                .IsUnicode(false)
+                .HasColumnName("Category");
+            entity.Property(e => e.StatusFlag)
+                .HasColumnName("StatusFlag");
+            entity.Property(e => e.AddedWhen)
+                .HasColumnType("datetime")
+                .HasColumnName("ADDED_WHEN");
+            entity.Property(e => e.ChangedWhen)
+                .HasColumnType("datetime")
+                .HasColumnName("CHANGED_WHEN");
+        });
+    }
+}