[FEATURE] Vim/emacs-style row navigation in agent view (j/k, ctrl+n/p)

love agent view. one nit: row navigation is arrow-only — j/k or ctrl+n/ctrl+p would feel right at home in a terminal. alt+1..9 helps but only for the first 9.

Docs at https://code.claude.com/docs/en/agent-view list only ↑/↓ for moving between rows.