Runtime reflection

The UnrealCV runtime reflection implementation draws on the SPEAR project paper (https://arxiv.org/abs/2607.06701) and source repository (https://github.com/spear-sim/spear).

Use vreflect to inspect reflected Unreal objects, read nested properties, update writable values, and invoke JSON-parameterized functions. The command semantics, security considerations, and examples are maintained in Runtime reflection.