* feat(desktop): add Electron shell lifecycle Signed-off-by: QCYTSN <2558348385@qq.com> * docs(desktop): document shell security boundary Signed-off-by: QCYTSN <2558348385@qq.com> * fix(desktop): address shell lifecycle review Signed-off-by: QCYTSN <2558348385@qq.com> * fix(desktop): constrain backend executable resolution Signed-off-by: QCYTSN <2558348385@qq.com> --------- Signed-off-by: QCYTSN <2558348385@qq.com>