Tab key during QuestionPrompt/PermissionPrompt triggered agent_cycle
because CommandProvider useKeyboard handler lacked guards for active
modal state. Root cause: opentui fires all global keyboard handlers in
mount order (parent first), so parent handler processed Tab before
child could preventDefault.
Fix: suspend command keybinds while QuestionPrompt or PermissionPrompt
is active (matching existing autocomplete.tsx pattern), and add
defaultPrevented guard as defense-in-depth. Clamp suspendCount to >= 0
to prevent mismatched enable/disable calls.
11916aeea1