v0.21.0

What changed

• rpi stats -w is now a dashboard TUI. The live view shows CPU, memory, and temperature as separate cards — each with a large current value and its own mini line chart — replacing the previous single combined chart. The top strip now carries disk usage and uptime.
• The services table shows real per-container status. Each service row now has a status pill (running / restarting / unhealthy / …) driven by the container's actual Docker state and healthcheck, plus an inline memory bar scaled to the heaviest service. Against an older agent that doesn't report status, the pill shows a neutral placeholder instead of a made-up value.
• rpi doctor: the version-mismatch hint now points at the stale side — it tells you whether the CLI or the agent is the one behind, instead of a generic message.

Colours follow the raspberry theme and downgrade cleanly on terminals without truecolor; the dashboard adapts to smaller terminals (compact and minimal fallbacks) so it never overflows.

Internal

Rendering is split into a pure, unit-tested view-model (stats_view) and a rendering-only stats_tui; a new tui-big-text dependency draws the large card numbers; container state/health are threaded through ServiceStats/ServiceStatsDto, backward compatible with older agents via serde defaults.

Full Changelog: v0.20.1...v0.21.0