Toggle a Diagnostics panel with i, built on the Activity readout. It swaps
in for the Drive pane and shows the decoded critical_warning, power-on
hours, power cycles, unsafe shutdowns, media errors and available spare
with their change over the selection, and per-hour (Day) or per-day
(History) temperature min/avg/max, active/idle/powered-off/unknown split
and coverage. History bars draw reads beside writes while it is open, and a
set critical_warning shows as a badge in the endurance outlook without
affecting the projection. Counter deltas are withheld across a controller
segment change.
Implement Amber/Nord/High Contrast theme presets with XDG user-scoped
persistence and reduced motion toggle. Covers TPH-10 and preference
integration with TPH-2.
- preferences.py: safe load/save with XDG_CONFIG_HOME/fenris/preferences.json
- themes.py: three Textual Theme objects with graph colour roles
- TUI: t cycles presets, m toggles reduced motion, both persist across restart
- Status composition receives reduced_motion from preferences
- 56 new tests covering persistence, themes, TUI integration, CLI isolation
- All 590 existing tests continue to pass
xavierk