Final: Leplanner Controller/{pusht,reacher,tworooms}/controller.pt + density.pt

Clean structure

Clean structure: controllers/pusht_controller.pt, reacher_controller.pt, tworooms_controller.pt

Simplify README: clear per-env table, download code, clean structure

Paper-ready README: results PushT 98/92, Reacher 100, TwoRooms 100

Paper-ready README: results table, quick start, structure, citation (#1)

initial commit