Denylist hits ask the user (default deny, timeout) instead of only hard
rejecting when a policy hook is installed. Independent of YOLO soft-confirm;
session grants skip re-prompt for the same basename. CLI installs the hook
via install_cli_limit_hooks.
Add process-wide prompting backends for interactive human I/O; wire CLI
limit/confirm/workspace prompts through it. Expose ask_user, choose_user,
and form_user under tools/chat and include them in DEFAULT_TOOLS.