vm2 exposes host HTTPS credentials and TLS traffic through globalAgent

Summary vm2 3.11.6 exposes the host process's real `https.globalAgent` when a `NodeVM` is explicitly allowed to require `https`. The module is wrapped as read-only, but calls to methods on the shared agent still mutate the host object. Sandbox code can register a `free` listener and receive host request options and the host TLS socket whenever an unrelated host HTTPS request releases a pooled connection. In a contained test, sandbox code allowed only the `https` builtin: - read the host request's bearer token from the agent event; - attached a data listener to the released host TLS socket and read the next host response body in plaintext; - learned the private service host and port; - sent an attacker-chosen authenticated POST using the stolen host token; and - received confirmation that the service accepted the action. The host application never passed its credentials, request, response, socket, or destination into the sandbox. They crossed the boundary solely because vm2 exposes the process-global HTTPS agent instead of a sandbox-local network module instance. ### Details The vulnerable boundary is the default builtin loader in `lib/builtin.js`: ```js builtins.set(key, special ? special : vm => vm.readonly(hostRequire(key))); ``` The wrapper recursively exposes properties of the actual host module. For ordinary constants, a read-only proxy can be sufficient. It is not sufficient for process-global EventEmitter objects whose methods mutate internal state. `https.globalAgent`