Fix React error #130 by correcting Card component usage

- Fixed all Card components to use padding prop instead of className
- Updated padding values: p-4 -> sm, p-6 -> md, p-8 -> lg
- This resolves the React element type invalid error

🤖 Generated with [Claude Code](https://claude.ai/code)

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

frontend/src/pages/admin/EventDetailsPage.tsx

@@ -15,7 +15,7 @@ import {
   Copy,
   CheckCircle
 } from 'lucide-react';
-import { format, parseISO, differenceInDays, addDays } from 'date-fns';
+import { format, parseISO, differenceInDays } from 'date-fns';
 import { toast } from 'react-toastify';
 
 import { Button, Input, Card, Loading } from '../../components/common';
@@ -249,7 +249,7 @@ export const EventDetailsPage: React.FC = () => {
         {/* Left Column - Details */}
         <div className="lg:col-span-2 space-y-6">
           {/* Event Information */}
-          <Card className="p-6">
+          <Card padding="md">
             <h2 className="text-lg font-semibold text-neutral-900 mb-4">Event Information</h2>
             
             {isEditing ? (
@@ -325,7 +325,7 @@ export const EventDetailsPage: React.FC = () => {
           </Card>
 
           {/* Share Link */}
-          <Card className="p-6">
+          <Card padding="md">
             <h2 className="text-lg font-semibold text-neutral-900 mb-4">Share Link</h2>
             
             <div className="flex items-center gap-2">
@@ -352,7 +352,7 @@ export const EventDetailsPage: React.FC = () => {
 
           {/* Actions */}
           {!event.is_archived && (
-            <Card className="p-6">
+            <Card padding="md">
               <h2 className="text-lg font-semibold text-neutral-900 mb-4">Actions</h2>
               
               <div className="space-y-3">
@@ -380,7 +380,7 @@ export const EventDetailsPage: React.FC = () => {
 
         {/* Right Column - Statistics */}
         <div className="space-y-6">
-          <Card className="p-6">
+          <Card padding="md">
             <h2 className="text-lg font-semibold text-neutral-900 mb-4">Statistics</h2>
             
             {stats ? (
@@ -419,7 +419,7 @@ export const EventDetailsPage: React.FC = () => {
 
           {/* Archive Status */}
           {event.is_archived && (
-            <Card className="p-6">
+            <Card padding="md">
               <h2 className="text-lg font-semibold text-neutral-900 mb-4">Archive Status</h2>
               
               <div className="space-y-3">