Entity energy and fluids
entity.capability(host, &ENTITY_ENERGY, side) and entity.capability(host, &ENTITY_FLUIDS, side) reach a mod's
entity energy and fluid handlers (NeoForge 26.3's Capabilities.Energy.ENTITY and Capabilities.Fluid.ENTITY), where
side is the Option<Direction> of the entity the lookup reaches it from, None for no particular side. Vanilla
answers neither; register a provider with r.entity_capability(&ENTITY_ENERGY, "mymod:robot", |host, robot, side| …),
which is given that side and may answer differently for each. An entity capability's context is its key's second type:
() for ENTITY_ITEMS, Option<Direction> for these two and for ENTITY_AUTOMATION. The existing move_energy and move_resources transfer
between these and block or item handlers inside a transaction.