Add AI status badges to show verification status on prices

- Add ai_status column to price_history table (verified/corrected/null)
- Track AI verification status through scraper and scheduler
- Display badges next to prices:
  - ✓ AI (green): AI verified the price is correct
  - ⚡ AI (orange): AI corrected an incorrect price
- Show badges on Dashboard product cards and ProductDetail page
- Add legend explaining badges in Settings when AI Verification is enabled

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/components/AIStatusBadge.tsx

@@ -0,0 +1,60 @@
+import { AIStatus } from '../api/client';
+
+interface AIStatusBadgeProps {
+  status: AIStatus;
+  size?: 'small' | 'normal';
+}
+
+export default function AIStatusBadge({ status, size = 'normal' }: AIStatusBadgeProps) {
+  if (!status) return null;
+
+  const isSmall = size === 'small';
+  const fontSize = isSmall ? '0.65rem' : '0.75rem';
+  const padding = isSmall ? '0.1rem 0.3rem' : '0.15rem 0.4rem';
+
+  if (status === 'verified') {
+    return (
+      <span
+        style={{
+          display: 'inline-flex',
+          alignItems: 'center',
+          gap: '0.2rem',
+          fontSize,
+          padding,
+          borderRadius: '0.25rem',
+          backgroundColor: 'rgba(16, 185, 129, 0.15)',
+          color: '#10b981',
+          fontWeight: 500,
+        }}
+        title="AI verified this price is correct"
+      >
+        <span style={{ fontSize: isSmall ? '0.7rem' : '0.8rem' }}>✓</span>
+        AI
+      </span>
+    );
+  }
+
+  if (status === 'corrected') {
+    return (
+      <span
+        style={{
+          display: 'inline-flex',
+          alignItems: 'center',
+          gap: '0.2rem',
+          fontSize,
+          padding,
+          borderRadius: '0.25rem',
+          backgroundColor: 'rgba(245, 158, 11, 0.15)',
+          color: '#f59e0b',
+          fontWeight: 500,
+        }}
+        title="AI corrected this price (original scrape was incorrect)"
+      >
+        <span style={{ fontSize: isSmall ? '0.7rem' : '0.8rem' }}>⚡</span>
+        AI
+      </span>
+    );
+  }
+
+  return null;
+}

frontend/src/components/ProductCard.tsx

@@ -2,6 +2,7 @@ import { useState, useEffect } from 'react';
 import { Link } from 'react-router-dom';
 import { Product } from '../api/client';
 import Sparkline from './Sparkline';
+import AIStatusBadge from './AIStatusBadge';
 
 interface ProductCardProps {
   product: Product;
@@ -502,9 +503,12 @@ export default function ProductCard({ product, onDelete, onRefresh, isSelected,
           </span>
         ) : (
           <>
-            <span className="product-current-price">
-              {formatPrice(product.current_price, product.currency)}
-            </span>
+            <div style={{ display: 'flex', alignItems: 'center', gap: '0.375rem' }}>
+              <span className="product-current-price">
+                {formatPrice(product.current_price, product.currency)}
+              </span>
+              <AIStatusBadge status={product.ai_status} size="small" />
+            </div>
             {product.price_change_7d !== null && product.price_change_7d !== undefined && (
               <span className={`product-price-change ${priceChangeClass}`}>
                 {formatPriceChange(product.price_change_7d)} (7d)