feat(CUB-56): Agent State Database Migration

backend/Data/AppDbContext.cs

@@ -0,0 +1,29 @@
+using ControlCenter.Api.Configurations;
+using ControlCenter.Api.Entities;
+using Microsoft.EntityFrameworkCore;
+
+namespace ControlCenter.Api.Data;
+
+/// <summary>
+/// EF Core DbContext for the Control Center database.
+/// All table and column names use snake_case via explicit HasColumnName configuration.
+/// </summary>
+public class AppDbContext : DbContext
+{
+    public AppDbContext(DbContextOptions<AppDbContext> options) : base(options) { }
+
+    public DbSet<Agent> Agents => Set<Agent>();
+
+    protected override void OnModelCreating(ModelBuilder modelBuilder)
+    {
+        // Apply all entity type configurations from the Configurations namespace
+        modelBuilder.ApplyConfigurationsFromAssembly(typeof(AgentConfiguration).Assembly);
+
+        // Map the AgentStatus enum to a PostgreSQL enum type named "agent_status"
+        // This must be called after ApplyConfigurations to ensure the model is built
+        // before the enum mapping is applied.
+        modelBuilder.HasPostgresEnum<AgentStatus>();
+
+        base.OnModelCreating(modelBuilder);
+    }
+}

backend/Data/AppDbContextFactory.cs

@@ -0,0 +1,27 @@
+using Microsoft.EntityFrameworkCore;
+using ControlCenter.Api.Entities;
+
+namespace ControlCenter.Api.Data;
+
+/// <summary>
+/// Design-time factory for AppDbContext, used by EF Core tools (dotnet ef)
+/// to create migrations without requiring a running application.
+/// </summary>
+public class AppDbContextFactory : Microsoft.EntityFrameworkCore.Design.IDesignTimeDbContextFactory<AppDbContext>
+{
+    public AppDbContext CreateDbContext(string[] args)
+    {
+        var optionsBuilder = new DbContextOptionsBuilder<AppDbContext>();
+
+        // Connection string for design-time operations (migrations).
+        // In production, this comes from appsettings / environment variables.
+        var connectionString = "Host=localhost;Database=control_center;Username=postgres;Password=postgres";
+
+        optionsBuilder.UseNpgsql(connectionString, npgsqlOptions =>
+        {
+            npgsqlOptions.MigrationsAssembly(typeof(AppDbContext).Assembly.FullName);
+        });
+
+        return new AppDbContext(optionsBuilder.Options);
+    }
+}