MAJOR UPPDATE: "First Ai"

feat: add AI categorization for products and enhance user management

- Integrated AI service for category suggestions in receipt import and product management.
- Added premium subscription feature for users with corresponding API endpoints.
- Implemented admin interface for managing pending product suggestions.
- Enhanced user management to include premium status and corresponding UI updates.
- Updated database schema to support new fields for premium status and product status.

frontend/app/kvitto/ReceiptImportClient.tsx

@@ -2,6 +2,14 @@
 
 import { useRef, useState, useEffect } from 'react';
 
+type CategorySuggestion = {
+  categoryId: number;
+  categoryName: string;
+  path: string;
+  confidence: 'high' | 'medium' | 'low';
+  usedFallback: boolean;
+};
+
 type ParsedItem = {
   rawName: string;
   quantity: number;
@@ -11,6 +19,7 @@ type ParsedItem = {
   matchedProductName?: string;
   suggestedProductId?: number;
   suggestedProductName?: string;
+  categorySuggestion?: CategorySuggestion;
 };
 
 type Product = { id: number; name: string; canonicalName: string | null };
@@ -27,6 +36,7 @@ type RowState = {
   editQty: string;
   editUnit: string;
   matchSource: 'alias' | 'suggestion' | 'manual' | 'none';
+  categorySuggestion?: CategorySuggestion;
 };
 
 const UNITS = ['st', 'kg', 'g', 'l', 'dl', 'cl', 'ml', 'förp', 'pak', 'burk', 'flaska'];
@@ -116,6 +126,7 @@ export default function ReceiptImportClient() {
             editQty: String(item.quantity),
             editUnit: item.unit,
             matchSource: 'none',
+            categorySuggestion: item.categorySuggestion,
           };
         }),
       );
@@ -272,6 +283,13 @@ export default function ReceiptImportClient() {
                       {UNITS.map((u) => <option key={u} value={u}>{u}</option>)}
                     </select>
                   </div>
+                  {row.categorySuggestion && row.matchSource === 'none' && (
+                    <div style={{ marginTop: '0.5rem', fontSize: '0.8rem', color: '#7c3aed', background: '#f5f3ff', border: '1px solid #ddd6fe', borderRadius: '5px', padding: '4px 8px', display: 'inline-flex', alignItems: 'center', gap: '0.4rem' }}>
+                      <span>✨</span>
+                      <span>AI-förslag: <strong>{row.categorySuggestion.path}</strong></span>
+                      {row.categorySuggestion.usedFallback && <span style={{ color: '#b45309' }}>(osäker)</span>}
+                    </div>
+                  )}
                   {row.selectedProductId !== '' && row.matchSource !== 'alias' && (
                     <label style={{ display: 'flex', alignItems: 'center', gap: '0.4rem', marginTop: '0.5rem', fontSize: '0.82rem', color: '#555', cursor: 'pointer' }}>
                       <input type="checkbox" checked={row.saveAlias} onChange={(e) => updateRow(i, { saveAlias: e.target.checked })} />