feat: UI animation enhancements across all major pages

P1 - Critical UX feedback:
- Add scale-in + slide-up-in entrance animations to profile popover and notification panel
- Port SmoothedProgressBar to EcommercePage (4 generation tools: clone, detail, tryOn, productSet)
- Add result-reveal stagger animation to ecommerce result grids
- Add heart-pop spring animation to CommunityPage favorite toggle

P2 - Visual polish:
- Add scroll-entrance IntersectionObserver animations for HomePage feature sections and experience section
- Add chat-message-in entrance animation to WorkbenchPage message rows
- Fix prefers-reduced-motion accessibility in WelcomeSplash canvas (skip animation, instant entry)

P3 - CSS consolidation:
- Remove conflicting .page-motion definition from legacy-pages.css (keep translateY version from legacy-components.css)
- Consolidate skeleton-shimmer: remove opacity-pulse keyframe from primitives.css, unify with gradient sweep
- Wire up --ease-spring token for heart-pop animation
- Add :active press states (scale 0.97) to topbar buttons, brand lockup

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

src/features/ecommerce/EcommerceProgressBar.tsx

@@ -0,0 +1,30 @@
+import { useSmoothedProgress } from "../../hooks/useSmoothedProgress";
+
+interface EcommerceProgressBarProps {
+  status: "idle" | "generating" | "done" | "failed" | string;
+  label?: string;
+}
+
+function mapStatus(status: string): "running" | "completed" | "failed" {
+  if (status === "done") return "completed";
+  if (status === "failed") return "failed";
+  if (status === "generating" || status === "modeling") return "running";
+  return "running";
+}
+
+export function EcommerceProgressBar({ status, label }: EcommerceProgressBarProps) {
+  const progress = mapStatus(status) === "running" ? 50 : 100;
+  const smoothed = useSmoothedProgress(progress, mapStatus(status));
+
+  if (status === "idle") return null;
+
+  return (
+    <div className="ecommerce-progress-bar">
+      <span className="ecommerce-progress-bar__label">{label || "AI 正在生成"}</span>
+      <div className="ecommerce-progress-bar__track">
+        <div className="ecommerce-progress-bar__fill" style={{ width: `${smoothed}%` }} />
+      </div>
+      <span className="ecommerce-progress-bar__value">{smoothed}%</span>
+    </div>
+  );
+}