fix: Multiple ADHD/Focus Tools fixes

Switch/Checkbox Styling:
- Exclude switches and checkboxes from larger-targets CSS
- Fix checkbox square aspect ratio when ADHD mode enabled
- Prevent padding from being applied to form controls

Quick Wins Count:
- Use settings.quickWinThreshold instead of hardcoded 15
- Match same filtering logic as QuickWinList component

Back Button Navigation:
- Use window.history.back() instead of setLocation('/')
- Works correctly when navigating from ADHD dashboard to sub-pages

Time Tracking (Break Reminder):
- Track only active browser time using Page Visibility API
- Reset accumulated time after 8 hours of inactivity
- Store/restore active time in localStorage properly
- No more 1500+ hour counts from leaving browser open

Sources:
- https://ui.shadcn.com/docs/theming (shadcn theming)
- https://ui.shadcn.com/docs/tailwind-v4 (Tailwind v4 updates)

client/src/pages/ADHDDashboardPage.tsx

@@ -45,11 +45,16 @@ export default function ADHDDashboardPage() {
     return updated.toDateString() === today.toDateString();
   }).length;
 
-  const quickWins = tasks.filter(t =>
-    t.status !== 'done' &&
-    t.estimatedDuration &&
-    t.estimatedDuration <= 15
-  ).length;
+  // Use same logic as QuickWinList for consistent count
+  const threshold = settings.quickWinThreshold || 15;
+  const quickWins = tasks.filter(t => {
+    if (t.status === 'done') return false;
+    // Only tasks without subtasks (leaf tasks)
+    if (tasks.some(parent => parent.parentTaskId === t.id)) return false;
+    // Filter by duration threshold (same as QuickWinList: threshold * 1.5)
+    if (t.estimatedDuration && t.estimatedDuration > threshold * 1.5) return false;
+    return true;
+  }).length;
 
   const features = [
     {
@@ -84,7 +89,7 @@ export default function ADHDDashboardPage() {
         <Button
           variant="ghost"
           size="icon"
-          onClick={() => setLocation('/')}
+          onClick={() => window.history.back()}
           className="shrink-0"
         >
           <ArrowLeft className="h-5 w-5" />

client/src/pages/BodyDoublingPage.tsx

@@ -28,7 +28,7 @@ export default function BodyDoublingPage() {
         <Button
           variant="ghost"
           size="icon"
-          onClick={() => setLocation('/')}
+          onClick={() => window.history.back()}
           className="shrink-0"
         >
           <ArrowLeft className="h-5 w-5" />

client/src/pages/QuickWinsPage.tsx

@@ -32,7 +32,7 @@ export default function QuickWinsPage() {
         <Button
           variant="ghost"
           size="icon"
-          onClick={() => setLocation('/')}
+          onClick={() => window.history.back()}
           className="shrink-0"
         >
           <ArrowLeft className="h-5 w-5" />

client/src/pages/SingleTaskPage.tsx

@@ -58,7 +58,7 @@ export default function SingleTaskPage() {
         <Button
           variant="ghost"
           size="icon"
-          onClick={() => setLocation('/')}
+          onClick={() => window.history.back()}
           className="shrink-0"
         >
           <ArrowLeft className="h-5 w-5" />