fix: Vertical tabs visibility and add mobile horizontal tabs

Fixed two critical issues with VerticalTabForm:

Issue #1: All sections showing at once
- Problem: className override was removing original classes
- Fix: Preserve originalClassName and append 'hidden' when inactive
- Now only active section is visible
- Inactive sections get 'hidden' class added

Issue #2: No horizontal tabs on mobile
- Added mobile horizontal tabs (lg:hidden)
- Scrollable tab bar with overflow-x-auto
- Active tab highlighted with bg-primary
- Icons + labels for each tab
- Separate mobile content area

Changes to VerticalTabForm.tsx:
1. Fixed className merging logic
   - Get originalClassName from child.props
   - Active: use originalClassName as-is
   - Inactive: append ' hidden' to originalClassName
   - Prevents className override issue

2. Added mobile layout
   - Horizontal tabs at top (lg:hidden)
   - Flex with gap-2, overflow-x-auto
   - flex-shrink-0 prevents tab squishing
   - Active state: bg-primary text-primary-foreground
   - Inactive state: bg-muted text-muted-foreground

3. Desktop layout (hidden lg:flex)
   - Vertical sidebar (w-56)
   - Content area (flex-1)
   - Scroll spy for desktop only

4. Mobile content area (lg:hidden)
   - No scroll spy (simpler)
   - Direct tab switching
   - Same visibility logic (hidden class)

Result:
✅ Only active section visible (desktop + mobile)
✅ Mobile has horizontal tabs
✅ Desktop has vertical sidebar
✅ Proper responsive behavior
✅ Tab switching works correctly

admin-spa/src/components/VerticalTabForm.tsx

@@ -66,20 +66,20 @@ export function VerticalTabForm({ tabs, children, className }: VerticalTabFormPr
   };
 
   return (
-    <div className={cn('flex gap-6', className)}>
-      {/* Vertical Tabs Sidebar */}
-      <div className="hidden lg:block w-56 flex-shrink-0">
-        <div className="sticky top-4 space-y-1">
+    <div className={cn('space-y-4', className)}>
+      {/* Mobile: Horizontal Tabs */}
+      <div className="lg:hidden">
+        <div className="flex gap-2 overflow-x-auto pb-2">
           {tabs.map((tab) => (
             <button
               key={tab.id}
               onClick={() => scrollToSection(tab.id)}
               className={cn(
-                'w-full text-left px-4 py-2.5 rounded-md text-sm font-medium transition-colors',
-                'flex items-center gap-3',
+                'flex-shrink-0 px-4 py-2 rounded-md text-sm font-medium transition-colors',
+                'flex items-center gap-2',
                 activeTab === tab.id
                   ? 'bg-primary text-primary-foreground'
-                  : 'text-muted-foreground hover:bg-muted hover:text-foreground'
+                  : 'bg-muted text-muted-foreground'
               )}
             >
               {tab.icon && <span className="w-4 h-4">{tab.icon}</span>}
@@ -89,18 +89,59 @@ export function VerticalTabForm({ tabs, children, className }: VerticalTabFormPr
         </div>
       </div>
 
-      {/* Content Area */}
-      <div
-        ref={contentRef}
-        className="flex-1 overflow-y-auto pr-2"
-      >
+      {/* Desktop: Vertical Layout */}
+      <div className="hidden lg:flex gap-6">
+        {/* Vertical Tabs Sidebar */}
+        <div className="w-56 flex-shrink-0">
+          <div className="sticky top-4 space-y-1">
+            {tabs.map((tab) => (
+              <button
+                key={tab.id}
+                onClick={() => scrollToSection(tab.id)}
+                className={cn(
+                  'w-full text-left px-4 py-2.5 rounded-md text-sm font-medium transition-colors',
+                  'flex items-center gap-3',
+                  activeTab === tab.id
+                    ? 'bg-primary text-primary-foreground'
+                    : 'text-muted-foreground hover:bg-muted hover:text-foreground'
+                )}
+              >
+                {tab.icon && <span className="w-4 h-4">{tab.icon}</span>}
+                {tab.label}
+              </button>
+            ))}
+          </div>
+        </div>
+
+        {/* Content Area - Desktop */}
+        <div
+          ref={contentRef}
+          className="flex-1 overflow-y-auto pr-2"
+        >
+          {React.Children.map(children, (child) => {
+            if (React.isValidElement(child) && child.props['data-section-id']) {
+              const sectionId = child.props['data-section-id'];
+              const isActive = sectionId === activeTab;
+              const originalClassName = child.props.className || '';
+              return React.cloneElement(child as React.ReactElement<any>, {
+                ref: (el: HTMLElement) => registerSection(sectionId, el),
+                className: isActive ? originalClassName : `${originalClassName} hidden`.trim(),
+              });
+            }
+            return child;
+          })}
+        </div>
+      </div>
+
+      {/* Mobile: Content Area */}
+      <div className="lg:hidden">
         {React.Children.map(children, (child) => {
           if (React.isValidElement(child) && child.props['data-section-id']) {
             const sectionId = child.props['data-section-id'];
             const isActive = sectionId === activeTab;
+            const originalClassName = child.props.className || '';
             return React.cloneElement(child as React.ReactElement<any>, {
-              ref: (el: HTMLElement) => registerSection(sectionId, el),
-              className: isActive ? '' : 'hidden',
+              className: isActive ? originalClassName : `${originalClassName} hidden`.trim(),
             });
           }
           return child;