chore(ui): disable session conversion button

Author: ymkiux

web-ui/partials/index/panel-sessions.html

@@ -208,7 +208,7 @@
                                         <button
                                             class="btn-session-export"
                                             @click="convertSession(activeSession)"
-                                            :disabled="!activeSession || isDerivedSession(activeSession) || sessionConverting[getSessionExportKey(activeSession)] || (activeSession.source !== 'codex' && activeSession.source !== 'claude')">
+                                            :disabled="true">
                                             {{ (activeSession && sessionConverting[getSessionExportKey(activeSession)]) ? t('sessions.preview.converting') : t('sessions.preview.convert') }}
                                         </button>
                                         <button