fix: move checksum to HTTP opts, fix mismatch retry, scope get_download_speed to aggregate-only

pkg/protocol/http/model_test.go

@@ -0,0 +1,15 @@
+package http
+
+import "testing"
+
+func TestOptsExtra_Checksum(t *testing.T) {
+	extra := &OptsExtra{
+		Checksum: &ChecksumOption{
+			Algorithm: "sha256",
+			Expected:  "abcdef1234567890",
+		},
+	}
+	if extra.Checksum.Algorithm != "sha256" || extra.Checksum.Expected != "abcdef1234567890" {
+		t.Fatalf("unexpected checksum: %+v", extra.Checksum)
+	}
+}