feat(libero): register 130 native tasks via get_task_class (library-free)

roboverse_pack.tasks.libero_native.registered: a BaseTaskEnv wrapper around the
self-contained native task, registered as libero_native/<suite>/<task> from a
shipped _tasks.json (cheap import; scene+assets loaded lazily on instantiation
from roboverse_data / HF). reset/step (OSC delta + gripper) / success (ported
BDDL checker) / render on mujoco+numpy -- get_task_class resolves and runs it
with libero/robosuite deleted. migrate now bundles the deterministic seed=0
BDDL reset state into each goal.json; native_task.from_vendored loads it.
+2 tests.

Author: geng-haoran