Refactor database connection handling and update Docker Compose environment variables #5

Api/Program.cs

@@ -39,8 +39,13 @@ namespace Api
             });
             builder.Services.AddControllers();
             // Add DbContext with SQL Server
+            // Allow connection string to be set via environment variable (e.g., in Docker)
+            var envConnectionString = Environment.GetEnvironmentVariable("DB_CONNECTION_STRING");
+            var connectionString = !string.IsNullOrWhiteSpace(envConnectionString)
+                ? envConnectionString
+                : builder.Configuration.GetConnectionString("DefaultConnection");
             builder.Services.AddDbContext<AppDbContext>(options =>
-                options.UseSqlServer(builder.Configuration.GetConnectionString("DefaultConnection")));
+                options.UseSqlServer(connectionString));
             // Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
             builder.Services.AddEndpointsApiExplorer();
             builder.Services.AddSwaggerGen();