Implements keyboard-first Panes TUI per spec section 7: - One dense screen: headline band, usage-history, drive-health, service strip - Bindings p/r/c/d/q with pause-asks/resume-doesnt asymmetry - Privileged actions via terminal-attached fenris-monitor subprocess - Disclosures view, empty-store greeting, first-run opt-in - 35 headless tests: CI-1 state matrix, TUI-1/TUI-4 layout, CI-4, IN-3 Blocker #27 resolved. Closes #28