feat(web): complete V21 UI redesign for all pages

- Replaced Ant Design Card/Layout with V21-compliant components
- Updated Header, MainLayout to V21 sticky top navigation
- Redesigned WorkspaceList, ProjectAssets, ProjectResults, ProjectTitles, ProjectVoices, ProjectGeneration with V21 card/grid system
- Added V21 color scheme, typography, spacing, pill badges, vertical/video cards
- Updated Login page and Plans subscription page to V21 design
- CSS-only styling without Ant Design overrides where possible

apps/web/src/pages/workspace/ProjectGeneration.css

@@ -0,0 +1,78 @@
+/* V21 视频剪辑 */
+.xx-project-generation {
+}
+
+.xx-template-grid {
+  display: grid;
+  grid-template-columns: repeat(4, 1fr);
+  gap: 14px;
+}
+
+@media (max-width: 1200px) {
+  .xx-template-grid {
+    grid-template-columns: repeat(3, 1fr);
+  }
+}
+
+@media (max-width: 768px) {
+  .xx-template-grid {
+    grid-template-columns: repeat(2, 1fr);
+  }
+}
+
+.xx-choice {
+  position: relative;
+  border: 2px solid #e2e8f0;
+  border-radius: 18px;
+  padding: 14px;
+  background: white;
+  cursor: pointer;
+  transition: all 0.2s;
+}
+
+.xx-choice:hover {
+  border-color: #4f46e5;
+}
+
+.xx-choice.selected {
+  border-color: #4f46e5;
+  box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.16);
+}
+
+.check {
+  position: absolute;
+  right: -7px;
+  top: -7px;
+  width: 26px;
+  height: 26px;
+  border-radius: 50%;
+  background: #4f46e5;
+  color: white;
+  display: grid;
+  place-items: center;
+  font-weight: 900;
+}
+
+.cover {
+  height: 78px;
+  border-radius: 14px;
+  display: grid;
+  place-items: center;
+  color: white;
+  font-size: 28px;
+  margin-bottom: 10px;
+}
+
+.xx-choice b {
+  font-size: 15px;
+  font-weight: 850;
+  color: #0f172a;
+  display: block;
+}
+
+.xx-choice p {
+  margin: 5px 0 0;
+  color: #64748b;
+  font-size: 12px;
+  line-height: 1.4;
+}