Address review: the gate module docstring now states the actual evaluation
contexts (config after injections against the plugin context, disabled at
every mount decision against the loader context); metadataExpressionErrors
rejects expressions nested below disabled and syntax-checks the disabled
expression itself so an unparseable gate fails at the gate instead of the
boot. The tutorial's !!js claims follow, and the loader note moves to
implemented/architecture with its inbound links retargeted.