Route desktop codec diagnostics through the shared log

Quiet capability probes, preserve runtime errors, and register the desktop portal application. Add logging and desktop launcher regression coverage.

tools/chatgui/src/desktop_integration.cpp

@@ -0,0 +1,38 @@
+#include "desktop_integration.h"
+#include "debug_config.h"
+#include <QDir>
+#include <QSaveFile>
+#include <QStandardPaths>
+
+bool registerDesktopApplication(const QString& executable) {
+#ifdef Q_OS_LINUX
+    const QString relative = QStringLiteral("applications/org.utun.vibechat.desktop");
+    if (!QStandardPaths::locate(QStandardPaths::GenericDataLocation, relative).isEmpty()) return true;
+    const QString root = QStandardPaths::writableLocation(QStandardPaths::GenericDataLocation);
+    const QString path = root + '/' + relative;
+    if (root.isEmpty() || !QDir().mkpath(root + "/applications")) {
+        DEBUG_WARN(DEBUG_CATEGORY_GENERAL, "Desktop registration: cannot create applications directory in %s", qPrintable(root));
+        return false;
+    }
+    // Exec сначала разбирается как desktop string, затем как командная строка; shell не используется.
+    QString command;
+    for (QChar c : executable) {
+        if (c == '%') command += "%%";
+        else { if (c == '\\' || c == '"' || c == '$' || c == '`') command += '\\'; command += c; }
+    }
+    command = '"' + command + '"';
+    command.replace("\\", "\\\\"); command.replace('\n', "\\n"); command.replace('\r', "\\r"); command.replace('\t', "\\t");
+    // GLib проверяет executable до раскрытия %%; env оставляет путь аргументом и корректно обрабатывает '%' в имени.
+    const QByteArray content = QString("[Desktop Entry]\nType=Application\nName=VibeChat\nExec=/usr/bin/env %1\n"
+        "Icon=applications-internet\nTerminal=false\nCategories=Network;InstantMessaging;\n").arg(command).toUtf8();
+    QSaveFile file(path);
+    if (!file.open(QIODevice::WriteOnly) || file.write(content) != content.size() || !file.commit()) {
+        DEBUG_WARN(DEBUG_CATEGORY_GENERAL, "Desktop registration failed path=%s: %s", qPrintable(path), qPrintable(file.errorString()));
+        return false;
+    }
+    DEBUG_INFO(DEBUG_CATEGORY_GENERAL, "Desktop application registered path=%s", qPrintable(path));
+#else
+    Q_UNUSED(executable);
+#endif
+    return true;
+}