Bash tool internals restructured into a factory-based interface

What

The Bash tool's internal implementation changed shape, though this is a structural rework rather than a new user-facing capability:

• It moved from a flat object with a single call method into a create() factory that returns separate validateInput, permissionCheckFailureDecision, checkPermissions, and call methods.
• These methods, which used to be defined directly on the tool object, are now returned per invocation from the create() factory, with a local helper deriving context (including shellPermission) for each call instead of it being passed in directly.

Why

This is an internal restructuring of how the Bash tool integrates with Claude Code's permission and validation pipeline. It doesn't change what the Bash tool does, but it changes how its context (like shell permissions) is computed per invocation, which is worth knowing if you're debugging or extending tool permission behavior.