fix(a11y): switch names, contrast floors, and chart-toggle pressed state

- Admin SettingsToggle: name the Radix switch via aria-label so it no longer
  announces as a bare 'switch, on/off' (one shared component, six call sites).
- Replace the phantom text-destructive-foreground / text-warning-foreground
  utilities with the vetted destructive pattern (bg-destructive text-white
  dark:bg-destructive/60) and a readable foreground on the warning wash — no
  more dead classes riding on cascade order.
- Drop the sub-AA opacity tiers: lab sparkline + titration marker off
  muted/70, state icons (query-error, chart empty/error, med sort) off
  muted/60 to the full token so they clear the light-theme floor.
- Chart range toggles expose aria-pressed (lab, custom-metric, health, mood,
  compliance) so the active window is conveyed to assistive tech.

src/components/charts/chart-empty-state.tsx

@@ -56,7 +56,7 @@ export function ChartEmptyState({
       style={height === undefined ? undefined : { height }}
     >
       <LineChartIcon
-        className="text-muted-foreground/60 h-8 w-8"
+        className="text-muted-foreground h-8 w-8"
         aria-hidden="true"
       />
       <p className="text-sm font-medium">{title}</p>

src/components/charts/chart-error-state.tsx

@@ -73,7 +73,7 @@ export function ChartErrorState({
       style={height === undefined ? undefined : { height }}
     >
       <AlertTriangle
-        className="text-muted-foreground/60 h-8 w-8"
+        className="text-muted-foreground h-8 w-8"
         aria-hidden="true"
       />
       <p className="text-sm font-medium">{title}</p>

src/components/charts/compliance-line-chart.tsx

@@ -90,6 +90,7 @@ export function ComplianceLineChart({
             <Button
               key={r.label}
               variant={activeRangePoints === r.points ? "default" : "ghost"}
+              aria-pressed={activeRangePoints === r.points}
               size="sm"
               className="min-h-11 px-3 text-xs"
               onClick={() => setActiveRangePoints(r.points)}

src/components/charts/health-chart.tsx

@@ -1666,6 +1666,7 @@ export function HealthChart({
               <Button
                 key={r.labelKey}
                 variant={rangePoints === r.points ? "default" : "ghost"}
+                aria-pressed={rangePoints === r.points}
                 size="sm"
                 className="min-h-11 px-2 text-xs sm:px-3"
                 onClick={() => {

src/components/charts/mood-chart.tsx

@@ -1050,6 +1050,7 @@ export function MoodChart({
               <Button
                 key={r.labelKey}
                 variant={rangePoints === r.points ? "default" : "ghost"}
+                aria-pressed={rangePoints === r.points}
                 size="sm"
                 className="min-h-11 px-2 text-xs sm:px-3"
                 onClick={() => setRangePoints(r.points)}