Improve admin UI and vendor invite experience

Enhanced the admin dashboard tab styling for better clarity. Refactored InviteVendorCard with improved UI, feedback, and clipboard copy functionality. Fixed vendor store ID update to send raw object instead of JSON string. Ensured product price formatting is robust against non-numeric values.

app/dashboard/admin/page.tsx

@@ -403,11 +403,12 @@ export default function AdminPage() {
       </div>
 
       <Tabs value={activeTab} onValueChange={setActiveTab} className="space-y-6">
-        <TabsList>
+        <TabsList className="bg-muted/20 p-1 border border-border/40 backdrop-blur-sm h-auto">
           <TabsTrigger
             value="analytics"
             onMouseEnter={() => handleTabHover("analytics")}
             onFocus={() => handleTabFocus("analytics")}
+            className="data-[state=active]:bg-background/80 data-[state=active]:backdrop-blur-sm data-[state=active]:text-foreground data-[state=active]:shadow-sm px-6 py-2 transition-all"
           >
             Analytics
           </TabsTrigger>
@@ -415,6 +416,7 @@ export default function AdminPage() {
             value="management"
             onMouseEnter={() => handleTabHover("management")}
             onFocus={() => handleTabFocus("management")}
+            className="data-[state=active]:bg-background/80 data-[state=active]:backdrop-blur-sm data-[state=active]:text-foreground data-[state=active]:shadow-sm px-6 py-2 transition-all"
           >
             Management
           </TabsTrigger>

app/dashboard/admin/vendors/page.tsx

@@ -61,7 +61,7 @@ export default function AdminVendorsPage() {
       setUpdating(true);
       await fetchClient(`/admin/vendors/${editingVendor._id}/store-id`, {
         method: 'PUT',
-        body: JSON.stringify({ storeId: newStoreId })
+        body: { storeId: newStoreId }
       });
 
       toast({