style(ui): full UX/UI + motion pass across storefront, admin, editor

- fix save-bar buttons to use shared app-button primitive (were unstyled)
- fix platform-nav-group border/radius via structural selectors, drop dead
  -middle/-right classes
- storefront widgets (hero/categories/product-carousel/footer-nav): design
  tokens, hover/focus states, 44px touch targets, entrance motion, reduced-
  motion guards
- admin dashboard cards + quick-actions: hover lift, entrance animation
- admin product-form gallery remove badge: hover/focus + expanded hit area
- project-editor section.shared button styles: hover/active/focus/disabled
  states + reduced-motion; section-switch fade-in motion

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/components/header/header.component.scss

@@ -553,34 +553,30 @@
   cursor: pointer;
   transition: background 0.3s ease;
   white-space: nowrap;
-  
+
+  &:not(:first-child) {
+    border-left: none;
+  }
+
+  &:first-child {
+    border-radius: 10px 0 0 10px;
+  }
+
+  &:last-child {
+    border-radius: 0 10px 10px 0;
+  }
+
   &:hover {
     background: #a1b4b5;
     color: #1e3c38;
   }
-  
+
   &.platform-active {
     background: #497671;
     color: #ffffff;
   }
 }
 
-.platform-nav-btn-left {
-  border-radius: 10px 0 0 10px;
-  padding: 6px 32px;
-}
-
-.platform-nav-btn-middle {
-  padding: 6px 40px;
-  border-left: none;
-}
-
-.platform-nav-btn-right {
-  border-radius: 0 10px 10px 0;
-  padding: 6px 28px;
-  border-left: none;
-}
-
 // Search Box
 .platform-search-wrapper {
   flex: 1;
@@ -975,7 +971,7 @@
     height: 32px;
   }
 
-  // Mobile Menu Backdrop — full-screen, blurred, blocks interaction
+  // Mobile Menu Backdrop <EFBFBD> full-screen, blurred, blocks interaction
   .platform-menu-backdrop {
     display: block;
     position: fixed;