The TUI had pure state and graph-viewport tests but nothing that rendered a
frame, so layout selection and panel presence were unprotected.
Eleven tests drive draw_dashboard through Ratatui's TestBackend across the
durable layouts: below the minimum width and height, the smallest usable
terminal, compact, large, multi-target, and the graph view in both target
modes, including active sample data, warning and error presentation, and
status-line state. Assertions are on visible text and layout facts rather
than full-screen snapshots.
Test-only change; production rendering is untouched.
Nils Andreas Svee
17d3fed7c5