feat(collector): capture additional smartctl diagnostics

Record host read and write commands, controller busy time, error log
entries, warning and critical temperature time, and thermal management
transitions from the existing smartctl -a -j acquisition. Schema 7 adds
nullable columns to samples so legacy rows read as unknown, and the
Diagnostics panel shows each counter with its change.

CHANGELOG.md

@@ -18,6 +18,7 @@ backfill releases from before this changelog.
 - Jump to the first or last point with Home and End on every graph, and a week at a time with PgUp and PgDn in the Day and History views.
 - Move through graph points with the mouse wheel, focus any panel by clicking it, and click the footer and activity tool chips to run their actions.
 - Open a Diagnostics panel with `i`: the decoded critical warning, power-on hours, power cycles, unsafe shutdowns, media errors and available spare with their change over the selection, plus hourly or daily temperature, 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.
+- Record more drive evidence from each collection run (host read and write commands, controller busy time, error log entries, warning and critical temperature time, and thermal management transitions where the drive reports them) and show it in the Diagnostics panel. Existing stores migrate automatically; earlier samples show n/a for the new counters.
 
 ### Changed