Fix isolated Go-side calls for Tengo callables and closures

Normalized profile

What this task asks for

Enable Go-side invocation of exported Tengo functions and closures while preserving runtime context and isolating compiled-instance state. Go-side invocation of script-defined functions and closures is broken: values exposed from a compiled script report callable but do not execute correctly outside the VM, and moving those callable values between compiled instances leaks the original runtime. Returned closures and composite values must stay callable. Cloned compiled instances and callable values assigned into another compiled instance must keep isolated state. Calling or mutating through one instance must not affect the source instance. If a transferred closure has already mutated captured locals, the destination must see those captures as they existed at transfer time while globals resolve against the destination instance. Apply the same isolation recursively to every callable reachable inside transferred arrays or maps, not only the top-level assigned value.