feat: duplicate detection + original URL in description

- Add original recipe URL to Mealie description (appended after blank line)
- Check for duplicate recipes on scrape (match orgURL or URL in description)
- Show warning with link to existing recipe if duplicate found
- User can still import anyway (warning only, not blocking)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/templates/import.html

@@ -232,7 +232,14 @@ async function scrapeRecipe() {
         currentRecipe = data.data;
         populatePreview(currentRecipe);
         document.getElementById('previewCard').classList.add('visible');
-        status.innerHTML = '<span class="text-success">✓ Beolvasva</span>';
+
+        if (data.duplicate) {
+            status.innerHTML = '<span class="text-warning">⚠ Ez a recept már létezik Mealie-ben: '
+                + '<a href="' + escHtml(data.duplicate.url) + '" target="_blank" style="color:var(--accent)">'
+                + escHtml(data.duplicate.name) + '</a></span>';
+        } else {
+            status.innerHTML = '<span class="text-success">✓ Beolvasva</span>';
+        }
     } catch (e) {
         status.innerHTML = '<span class="text-danger">Hálózati hiba: ' + e.message + '</span>';
     }