feat(header): rings for CPU and MEM in the Compact style (#426)

Compact now draws every reading the same way, ring then label then
value: CPU and MEM get an accent ring (red past 80%, like their value)
in place of the sparklines, the plan windows keep their green, yellow
or red rings, the dot separators go, and both pills share one label and
one value style. The sparkline markup, history and CSS are removed.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/web/schemas.ts

@@ -1457,7 +1457,7 @@ export const SettingsUpdateSchema = z
      * How the header draws its WS / CPU / MEM / plan-usage cluster. Display key
      * (per-device), desktop only (the cluster is hidden below 768px).
      * 'classic' = the bars and the 5H · 7D chip, as before
-     * 'compact' = one system pill with sparklines plus a plan-usage ring pill
+     * 'compact' = two pills (WS/CPU/MEM, the plan windows), a ring beside every value
      * 'tiles'   = label over value with a bar underneath, no icons. The default.
      */
     headerStatsStyle: z.enum(['classic', 'compact', 'tiles']).optional(),