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/themes/dark-green.css

@@ -3990,6 +3990,13 @@
   isolation: isolate;
   break-inside: avoid;
   aspect-ratio: 4 / 5;
+  transition: transform 200ms var(--ease-out-expo, cubic-bezier(0.16, 1, 0.3, 1)),
+              box-shadow 200ms ease;
+}
+
+.web-shell[data-ui-theme="dark-green"] .community-page .community-case-card--mosaic:hover {
+  transform: scale(1.02);
+  box-shadow: 0 8px 24px rgb(0 0 0 / 20%);
 }
 
 .web-shell[data-ui-theme="dark-green"] .community-page .community-case-card--tile-0,