Deep-copy bindings before giving to actions/guards

Otherwise an action/guard could modify (non-primitive) binding values.

Start by tracing how bindings are passed into actions and guards, the entry points named in the issue. Check how non-primitive values are represented and copied, then verify that an action or guard cannot mutate the original bindings; the issue provides no file or test names, so the relevant tests must be located in the repository.

Written by the indexing model from the issue text.