Add activity tracking to prevent stall timeouts during message transfers

Add OnActivity callback to CopyDeps to prevent stall timeouts during large message transfers
Implement touchReader and touchWriter wrappers to call OnActivity during FETCH and APPEND operations
Add slow message logging to identify performance bottlenecks
Add test case to verify activity reporting during message transfers
Clean up orchestrator account reset code formatting

internal/imapx/copy_test.go

@@ -169,6 +169,56 @@ func TestCopyFolderPreservesInternalDate(t *testing.T) {
 	}
 }
 
+// TestCopyFolderReportsActivityDuringBody proves CopyFolder invokes OnActivity
+// while a message body is being transferred (FETCH/APPEND), not only between
+// messages. This is what keeps the orchestrator's stall watchdog from killing a
+// single large-but-live message whose transfer legitimately exceeds the stall
+// timeout: without an in-body activity signal, one slow message looks identical
+// to a wedged connection.
+func TestCopyFolderReportsActivityDuringBody(t *testing.T) {
+	ep := testEP(t)
+	ctx := context.Background()
+
+	seedInbox(t, ep, "actsrc@localhost", "p", 1)
+
+	src, err := Connect(ctx, ep)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() { _ = src.Logout().Wait() }()
+	if err := src.Login("actsrc@localhost", "p").Wait(); err != nil {
+		t.Fatal(err)
+	}
+
+	dst, err := Connect(ctx, ep)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() { _ = dst.Logout().Wait() }()
+	if err := dst.Login("actdst@localhost", "p").Wait(); err != nil {
+		t.Fatal(err)
+	}
+
+	var activity int
+	deps := CopyDeps{
+		IsMigrated:   func(string) (bool, error) { return false, nil },
+		MarkMigrated: func(_, _ string) error { return nil },
+		OnProgress:   func(_, _ int) {},
+		OnActivity:   func() { activity++ },
+	}
+
+	r, err := CopyFolder(ctx, src, dst, "INBOX", "INBOX", deps)
+	if err != nil {
+		t.Fatalf("CopyFolder: %v", err)
+	}
+	if r.Copied != 1 {
+		t.Fatalf("copied=%d want 1", r.Copied)
+	}
+	if activity == 0 {
+		t.Fatal("OnActivity never called during body transfer")
+	}
+}
+
 // Требует два ящика на greenmail. Первый запуск копирует N, второй — 0 (все skipped).
 func TestCopyFolderIdempotent(t *testing.T) {
 	ep := testEP(t) // plain greenmail