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/features/ecommerce/EcommercePage.tsx

@@ -2819,7 +2819,8 @@ function ProductClonePage(_props: ProductClonePageProps = {}) {
 
         <aside
           id={isCloneTool ? "ecommerce-clone-settings-panel" : undefined}
-          className="product-clone-panel"
+          className={`product-clone-panel tool-panel-enter`}
+          key={activeTool}
           aria-label={`${pageLabel}参数`}
           aria-hidden={isCloneTool && isCloneSettingsCollapsed ? true : undefined}
         >