feat: UI interaction polish — exit animations, hover effects, directional transitions

- Add AnimatedPanel component with CSS transition-based enter/exit for
  Profile popover and Notification panel (140ms scale+fade)
- Add nav-activate-pulse animation for floating-nav active indicator (320ms glow)
- Add tool-panel-fade-in crossfade when switching ecommerce tools
- Add carousel-card-label slide-up-in 260ms on active carousel card
- Add feature-visual img hover scale(1.03)+brightness, experience-route hover translateY(-2px)
- Add community-case-card--mosaic hover scale(1.02)+shadow lift
- Add directional PageTransition: forward→slideX(20px), backward→slideX(-20px)
- Move vite proxy target from hardcoded IP to VITE_DEV_PROXY env variable
- Add .env.example for developer onboarding

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/styles/components/motion.css

@@ -34,6 +34,11 @@
   }
 }
 
+/* 260ms variant for carousel labels */
+.slide-up-in-260 {
+  animation: slide-up-in 260ms var(--ease-out-expo, cubic-bezier(0.16, 1, 0.3, 1)) both;
+}
+
 @keyframes backdrop-in {
   from { opacity: 0; }
   to { opacity: 1; }
@@ -111,6 +116,36 @@
   animation: chat-message-in 220ms var(--ease-out-expo, cubic-bezier(0.16, 1, 0.3, 1)) both;
 }
 
+/* AnimatedPanel: CSS transition-based enter/exit for popovers */
+.animated-panel {
+  opacity: 0;
+  transform: scale(0.95) translateY(8px);
+  transition:
+    opacity 140ms var(--ease-out-expo, cubic-bezier(0.16, 1, 0.3, 1)),
+    transform 140ms var(--ease-out-expo, cubic-bezier(0.16, 1, 0.3, 1));
+  pointer-events: none;
+}
+
+.animated-panel.is-visible {
+  opacity: 1;
+  transform: scale(1) translateY(0);
+  pointer-events: auto;
+}
+
+/* Ecommerce tool panel crossfade on tool switch */
+@keyframes tool-panel-fade-in {
+  from {
+    opacity: 0;
+  }
+  to {
+    opacity: 1;
+  }
+}
+
+.tool-panel-enter {
+  animation: tool-panel-fade-in 180ms var(--ease-out-expo, cubic-bezier(0.16, 1, 0.3, 1)) both;
+}
+
 /* Stagger utility: apply to parent, children get delayed entrance */
 .motion-stagger > * {
   animation: list-item-in 280ms var(--ease-out-expo, cubic-bezier(0.16, 1, 0.3, 1)) both;