Advanced Gantt Chart Modification( Panning, Heirarchy and Timelines)

hello every one ,
I was working on Gantt Chart (DAVID BACCI) to add multiple modification on it.So, I am trying to add more levels of hierarchy on it beside adding actual timeline with the planned timeline and I am trying to add panning and zooming features on the Gantt part only not the table.
Actually, i succeeded to add Actual timeline to it with lighter color under each planned timeline.

but i am still have a conflict to add zooming and panning features to it and to add levels of hierarchy to expand and collapse on.
So could anyone help me regarding this Deneb is in Vega code not in Vega lite??
and maybe have another question if there are ways to convert from Vega to Vega lite?
Thanks.
Gantt_MOD_3.pbix (1.5 MB)