Add ambient dashboard background: drifting orbs, noise texture, vignette, card breathe

Three layered effects to make the dashboard feel alive:
1. DashboardAmbient: two accent-colored drifting orbs at very low opacity
   (0.04/0.025) with 120px blur — subtle depth and movement
2. Noise texture + radial vignette via CSS pseudo-elements — breaks the
   flat digital surface and draws focus to center content
3. Card breathe animation: data-driven 4s pulsing glow on CalendarWidget
   (when event in progress) and TodoWidget (when overdue todos exist)

All effects respect prefers-reduced-motion, use accent CSS vars (works
with any user-chosen accent color), and are GPU-composited (transform +
opacity only) for negligible performance cost.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/components/dashboard/CalendarWidget.tsx

@@ -50,8 +50,10 @@ export default function CalendarWidget({ events }: CalendarWidgetProps) {
     return () => clearInterval(interval);
   }, []);
 
+  const hasCurrentEvent = events.some((e) => getEventTimeState(e, clientNow) === 'current');
+
   return (
-    <Card className="hover:shadow-lg hover:shadow-accent/5 hover:border-accent/20 transition-all duration-200">
+    <Card className={cn('hover:shadow-lg hover:shadow-accent/5 hover:border-accent/20 transition-all duration-200', hasCurrentEvent && 'animate-card-breathe')}>
       <CardHeader>
         <CardTitle className="flex items-center gap-2">
           <div className="p-1.5 rounded-md bg-purple-500/10">

frontend/src/components/dashboard/DashboardAmbient.tsx

@@ -0,0 +1,30 @@
+/**
+ * Muted ambient background for the dashboard.
+ * Two accent-colored drifting orbs at very low opacity — adds depth
+ * and movement without distracting from content. Reuses the same
+ * drift keyframes as the login AmbientBackground but at ~25% opacity.
+ */
+export default function DashboardAmbient() {
+  return (
+    <div className="pointer-events-none fixed inset-0 -z-10 overflow-hidden" aria-hidden="true">
+      {/* Primary orb — top-left drift */}
+      <div
+        className="absolute h-[600px] w-[600px] rounded-full opacity-[0.04] blur-[120px] animate-drift-1"
+        style={{
+          background: 'radial-gradient(circle, hsl(var(--accent-color)) 0%, transparent 70%)',
+          top: '-5%',
+          left: '-10%',
+        }}
+      />
+      {/* Secondary orb — bottom-right drift */}
+      <div
+        className="absolute h-[450px] w-[450px] rounded-full opacity-[0.025] blur-[120px] animate-drift-2"
+        style={{
+          background: 'radial-gradient(circle, hsl(var(--accent-color)) 0%, transparent 70%)',
+          bottom: '5%',
+          right: '-5%',
+        }}
+      />
+    </div>
+  );
+}

frontend/src/components/dashboard/DashboardPage.tsx

@@ -16,6 +16,7 @@ import DayBriefing from './DayBriefing';
 import CountdownWidget from './CountdownWidget';
 import TrackedProjectsWidget from './TrackedProjectsWidget';
 import AlertBanner from './AlertBanner';
+import DashboardAmbient from './DashboardAmbient';
 import EventForm from '../calendar/EventForm';
 import TodoForm from '../todos/TodoForm';
 import ReminderForm from '../reminders/ReminderForm';
@@ -164,7 +165,8 @@ export default function DashboardPage() {
     : null;
 
   return (
-    <div className="flex flex-col h-full">
+    <div className="flex flex-col h-full dashboard-ambient">
+      <DashboardAmbient />
       {/* Header — greeting + date + quick add */}
       <div className="px-4 md:px-6 pt-4 sm:pt-6 pb-1 sm:pb-2 flex items-center justify-between">
         <div>

frontend/src/components/dashboard/TodoWidget.tsx

@@ -48,8 +48,10 @@ export default function TodoWidget({ todos }: TodoWidgetProps) {
     onError: () => toast.error('Failed to complete todo'),
   });
 
+  const hasOverdue = todos.some((t) => isPast(endOfDay(new Date(t.due_date))));
+
   return (
-    <Card className="h-full hover:shadow-lg hover:shadow-accent/5 hover:border-accent/20 transition-all duration-200">
+    <Card className={cn('h-full hover:shadow-lg hover:shadow-accent/5 hover:border-accent/20 transition-all duration-200', hasOverdue && 'animate-card-breathe')}>
       <CardHeader>
         <CardTitle className="flex items-center gap-2">
           <div className="p-1.5 rounded-md bg-blue-500/10">

frontend/src/index.css

@@ -455,6 +455,41 @@ form[data-submitted] input:invalid + button {
 .animate-slide-in-row { animation: slide-in-row 250ms ease-out both; }
 .animate-content-reveal { animation: content-reveal 400ms ease-out both; }
 
+/* ── Dashboard ambient layers ── */
+
+/* SVG noise texture — adds tactile depth to flat dark backgrounds */
+.dashboard-ambient::before {
+  content: '';
+  position: fixed;
+  inset: 0;
+  z-index: -1;
+  opacity: 0.03;
+  pointer-events: none;
+  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
+  background-repeat: repeat;
+  background-size: 256px 256px;
+}
+
+/* Radial vignette — darkens edges, draws focus to center content */
+.dashboard-ambient::after {
+  content: '';
+  position: fixed;
+  inset: 0;
+  z-index: -1;
+  pointer-events: none;
+  background: radial-gradient(ellipse at center, transparent 40%, rgba(0, 0, 0, 0.35) 100%);
+}
+
+/* Card breathing glow — data-aware "alive" pulse for urgent cards */
+@keyframes card-breathe {
+  0%, 100% { box-shadow: 0 0 0 0 hsl(var(--accent-color) / 0.05); }
+  50% { box-shadow: 0 0 16px 2px hsl(var(--accent-color) / 0.10); }
+}
+
+.animate-card-breathe {
+  animation: card-breathe 4s ease-in-out infinite;
+}
+
 /* Respect reduced motion preferences */
 @media (prefers-reduced-motion: reduce) {
   *, *::before, *::after {