Rework task execution to be synchronous within a single tick.
Scheduling boundaries are now defined by `cycle` nodes, which
replace the previous `repeat` decorator. All tasks are executed
immediately when scheduled, and parent/child propagation is
handled inline.
The `LegacyTreeDef` type and its normalization path have been removed.
All tree definitions must now use the factory functions (`leaf`,
`sequential`, `parallel`, `selector`, `random`, `repeat`). The
`TreeDef` type is now simply `TaskEntityDef`.
hyper
hypercross