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/animtimer.cpp

@@ -0,0 +1,61 @@
+#include "animtimer.h"
+#include "lottieicon.h"
+#include "debug_ui.h"
+
+AnimTimer::AnimTimer() {
+    m_timer.setInterval(33);
+    connect(&m_timer, &QTimer::timeout, this, &AnimTimer::onTimer);
+    m_timer.start();
+}
+
+AnimTimer *AnimTimer::instance() {
+    static AnimTimer s;
+    return &s;
+}
+
+void AnimTimer::shutdown() {
+    instance()->m_timer.stop();
+    instance()->m_icons.clear();
+    DEBUG_INFO(DEBUG_CATEGORY_GENERAL, "AnimTimer: shutdown");
+}
+
+void AnimTimer::registerIcon(const QString &key, LottieIcon *icon) {
+    m_icons.insert(key, icon);
+}
+
+void AnimTimer::unregisterIcon(const QString &key) {
+    m_icons.remove(key);
+}
+
+LottieIcon *AnimTimer::icon(const QString &key) const {
+    return m_icons.value(key, nullptr);
+}
+
+void AnimTimer::activate() {
+    if (m_activeRef++ == 0) {
+        for (auto *icon : m_icons)
+            icon->advanceFrame();
+        emit ticked();
+    }
+}
+
+void AnimTimer::deactivate() {
+    if (m_activeRef > 0) m_activeRef--;
+}
+
+void AnimTimer::onTimer() {
+    if (m_activeRef <= 0) return;
+    for (auto *icon : m_icons)
+        icon->advanceFrame();
+    emit ticked();
+}
+
+void AnimTimer::logRegisteredIcons() const {
+    for (auto it = m_icons.constBegin(); it != m_icons.constEnd(); ++it) {
+        LottieIcon *icon = it.value();
+        GUI_INFO("LottieIcon: path=%s frames=%d size=%dx%d tgsSize=%d valid=%d",
+                 qPrintable(it.key()), icon->frameCount(),
+                 icon->originalSize().width(), icon->originalSize().height(),
+                 icon->tgsSize(), (int)icon->isValid());
+    }
+}