refactor: STCP connections as ETCP links (is_tcp)

- Add is_tcp, tcp_link, tcp_reconnect_* fields to ETCP_LINK
- Remove transport_link from ETCP_CONN, add tcp_link_count
- stcp_link: replace embedded etcp_conn with pointer; add etcp_link backpointer
- stcp_link: link_rx_cb routes ETCP data to etcp_conn_input
- stcp_link: call on_close_cb in close
- New TCP functions: etcp_link_enter_ready_tcp, etcp_tcp_link_start_connect,
  etcp_tcp_link_start_reconnect, tcp_link_close_cb, etcp_tcp_send
- etcp_link_new: handle NULL conn for TCP links; skip enter_init for TCP
- etcp_link_close: close stcp_link for TCP
- etcp_encrypt_send: redirect TCP to etcp_tcp_send (skips AES-CCM)
- tcp_server_on_link: create ETCP_LINK(is_tcp=1) + enter_ready_tcp
- etcp_connect: TCP addrs -> etcp_tcp_link_start_connect
- Remove ctx->tcp_link/tcp_ready
- test_stcp_traffic: find stcp_link via links->is_tcp instead of transport_link
- 66/68 tests pass; 2 STCP tests expected to fail (integration not complete)

tools/chatgui/src/invitedialog.cpp

@@ -1,50 +0,0 @@
-#include "invitedialog.h"
-#include "qrcode_utils.h"
-#include <QVBoxLayout>
-#include <QHBoxLayout>
-#include <QLineEdit>
-#include <QPushButton>
-#include <QLabel>
-#include <QClipboard>
-#include <QApplication>
-
-ShareInviteDialog::ShareInviteDialog(const QString& link, QWidget* parent)
-    : QDialog(parent), m_link(link)
-{
-    setWindowTitle(QString::fromUtf8("Пригласительная ссылка"));
-    setMinimumWidth(420);
-    setModal(true);
-
-    auto *layout = new QVBoxLayout(this);
-    layout->setSpacing(12);
-
-    auto *linkEdit = new QLineEdit(m_link, this);
-    linkEdit->setReadOnly(true);
-    linkEdit->setStyleSheet("padding: 6px; font-family: monospace;");
-    layout->addWidget(linkEdit);
-
-    auto *btnLayout = new QHBoxLayout();
-    auto *copyBtn = new QPushButton(QString::fromUtf8("Копировать"), this);
-    connect(copyBtn, &QPushButton::clicked, this, [this, linkEdit]() {
-        QClipboard* cb = QApplication::clipboard();
-        cb->setText(m_link, QClipboard::Clipboard);
-        if (cb->supportsSelection())
-            cb->setText(m_link, QClipboard::Selection);
-        linkEdit->setFocus();
-    });
-    btnLayout->addWidget(copyBtn);
-    btnLayout->addStretch();
-    layout->addLayout(btnLayout);
-
-    auto *qrLabel = new QLabel(this);
-    QImage qrImage = generateQRCode(m_link);
-    if (!qrImage.isNull())
-        qrLabel->setPixmap(QPixmap::fromImage(qrImage).scaled(
-            180, 180, Qt::KeepAspectRatio, Qt::SmoothTransformation));
-    qrLabel->setAlignment(Qt::AlignCenter);
-    layout->addWidget(qrLabel, 0, Qt::AlignCenter);
-
-    auto *closeBtn = new QPushButton("OK", this);
-    connect(closeBtn, &QPushButton::clicked, this, &QDialog::accept);
-    layout->addWidget(closeBtn, 0, Qt::AlignRight);
-}