stcp: ed25519 pubkey exchange in handshake, fix instance destroy segfault, fix chat_tcp_test

- u_async.c: process immediate_queue BEFORE epoll_wait in uasync_poll
- stcp_link.c: defensive NULL etcp_conn/etcp_link in stcp_link_close
- utun_instance.c: move stcp_server_list_destroy_all to Phase J (before ETCP),
  add deferred drain in both Phase J and L
- stcp.h/c: STCP_HS_ENC_CLIENT 6→38, STCP_HS_ENC_SERVER 7→39,
  exchange ed25519_pubkey in both handshake directions
- etcp_connections.c: copy peer_ed25519 from STCP to ETCP_CONN in
  etcp_link_enter_ready_tcp; guard link->etcp in tcp_link_close_cb
- chat_sync.c: fix lk->conn NULL dereference for TCP links
- test_stcp.c: update stcp_server_create/stcp_client_connect callsites
- tools/chat_tcp_test: change transport udp→tcp

tools/chatgui/src/emojipanel.cpp

@@ -0,0 +1,162 @@
+#include "emojipanel.h"
+#include "emoji.h"
+#include "emojitabbar.h"
+#include "animtimer.h"
+#include "lottieicon.h"
+#include <QPushButton>
+#include <QScrollArea>
+#include <QTabWidget>
+#include <QGridLayout>
+#include <QHBoxLayout>
+#include <QVBoxLayout>
+#include <QPainter>
+#include <QTimer>
+
+namespace {
+
+class EmojiTabWidget : public QTabWidget {
+public:
+    using QTabWidget::setTabBar;
+};
+
+class EmojiButton : public QPushButton {
+public:
+    EmojiButton(const EmojiData &data, QWidget *parent = nullptr)
+        : QPushButton(data.unicode, parent)
+        , m_data(data)
+    {
+        setFixedSize(32, 32);
+        setCursor(Qt::PointingHandCursor);
+        setStyleSheet(
+            "QPushButton { border: none; border-radius: 4px; font-size: 18px; background: transparent; }"
+            "QPushButton:hover { background: rgba(0,0,0,0.08); }"
+        );
+        if (data.type == EmojiType::Animation) {
+            setMouseTracking(true);
+            m_icon = AnimTimer::instance()->icon(data.animPath);
+            m_timer.setInterval(33);
+            connect(&m_timer, &QTimer::timeout, this, [this]() {
+                if (m_icon && m_icon->isValid()) {
+                    m_frame = (m_frame + 1) % m_icon->frameCount();
+                    update();
+                }
+            });
+        }
+    }
+    const QString &unicode() const { return m_data.unicode; }
+
+protected:
+#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
+    void enterEvent(QEnterEvent *e) override {
+#else
+    void enterEvent(QEvent *e) override {
+#endif
+        QPushButton::enterEvent(e);
+        if (m_icon && m_icon->isValid()) {
+            m_hovered = true;
+            m_frame = 0;
+            m_timer.start();
+        }
+    }
+    void leaveEvent(QEvent *e) override {
+        QPushButton::leaveEvent(e);
+        m_hovered = false;
+        m_timer.stop();
+        update();
+    }
+    void paintEvent(QPaintEvent *e) override {
+        if (m_hovered && m_icon && m_icon->isValid()) {
+            QPainter p(this);
+            p.setRenderHint(QPainter::SmoothPixmapTransform);
+            int sz = qMin(width(), height()) - 4;
+            QImage frame = m_icon->renderFrame(m_frame, QSize(sz, sz));
+            int x = (width() - sz) / 2, y = (height() - sz) / 2;
+            p.drawImage(x, y, frame);
+        } else {
+            QPushButton::paintEvent(e);
+        }
+    }
+
+private:
+    EmojiData m_data;
+    LottieIcon *m_icon = nullptr;
+    QTimer m_timer;
+    int m_frame = 0;
+    bool m_hovered = false;
+};
+
+} // namespace
+
+EmojiPanel::EmojiPanel(QWidget *parent)
+    : QWidget(parent)
+{
+    setStyleSheet("EmojiPanel { background: palette(window); }");
+    buildPanel(builtinEmojiSet());
+    hide();
+}
+
+void EmojiPanel::showEvent(QShowEvent *event) {
+    if (parentWidget()) {
+        setFixedHeight(qBound(200, parentWidget()->height() * 3 / 10, 800));
+    }
+    QWidget::showEvent(event);
+}
+
+void EmojiPanel::buildPanel(const QVector<EmojiCategory> &categories) {
+    auto *tabs = new EmojiTabWidget();
+    tabs->setDocumentMode(true);
+    tabs->setTabBar(new EmojiTabBar(tabs));
+    tabs->setStyleSheet("QTabWidget::pane { border: none; background: rgba(255,255,255,0.6); }");
+
+    for (const auto &cat : categories) {
+        tabs->addTab(buildCategoryPage(cat), cat.name);
+    }
+
+    auto *layout = new QVBoxLayout(this);
+    layout->setContentsMargins(0, 0, 0, 0);
+    layout->setSpacing(0);
+    layout->addWidget(tabs);
+}
+
+QWidget *EmojiPanel::buildCategoryPage(const EmojiCategory &cat) {
+    auto *scroll = new QScrollArea();
+    scroll->setWidgetResizable(true);
+    scroll->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
+    scroll->setStyleSheet("QScrollArea { border: none; }");
+
+    auto *container = new QWidget();
+    auto *grid = new QGridLayout(container);
+    grid->setContentsMargins(4, 4, 4, 4);
+    grid->setSpacing(2);
+
+    int cols = 9;
+    for (int i = 0; i < cat.items.size(); ++i) {
+        const auto &e = cat.items[i];
+        QPushButton *btn;
+        if (e.type == EmojiType::Animation)
+            btn = new EmojiButton(e, container);
+        else {
+            btn = new QPushButton(e.unicode, container);
+            btn->setFixedSize(32, 32);
+            btn->setCursor(Qt::PointingHandCursor);
+            btn->setStyleSheet(
+                "QPushButton { border: none; border-radius: 4px; font-size: 18px; background: transparent; }"
+                "QPushButton:hover { background: rgba(0,0,0,0.08); }"
+            );
+        }
+        btn->setToolTip(e.shortcode);
+        connect(btn, &QPushButton::clicked, this, &EmojiPanel::onEmojiClicked);
+        grid->addWidget(btn, i / cols, i % cols);
+    }
+    grid->setRowStretch(grid->rowCount(), 1);
+
+    scroll->setWidget(container);
+    return scroll;
+}
+
+void EmojiPanel::onEmojiClicked() {
+    auto *btn = qobject_cast<QPushButton *>(sender());
+    if (!btn) return;
+    auto *eb = dynamic_cast<EmojiButton *>(btn);
+    emit emojiSelected(eb ? eb->unicode() : btn->text());
+}