fix: resolve gallery authentication and redirect issues

- Fix useWatermarkSettings hook to use public API endpoint instead of admin endpoint
- Add hero_photo_id to gallery authentication response
- Prevent 401 errors on gallery pages from redirecting to admin login
- Gallery pages now correctly fetch settings without requiring admin auth

The main issue was that gallery pages were calling admin-only endpoints
which triggered 401 errors and caused redirects to the admin login page.

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

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

backend/src/routes/auth.js

@@ -119,7 +119,8 @@ router.post('/gallery/verify', [
         color_theme: event.color_theme,
         expires_at: event.expires_at,
         allow_user_uploads: event.allow_user_uploads,
-        upload_category_id: event.upload_category_id
+        upload_category_id: event.upload_category_id,
+        hero_photo_id: event.hero_photo_id
       }
     });
   } catch (error) {

frontend/src/hooks/useWatermarkSettings.ts

@@ -1,5 +1,5 @@
 import { useState, useEffect } from 'react';
-import { settingsService } from '../services/settings.service';
+import { api } from '../config/api';
 
 export function useWatermarkSettings() {
   const [watermarkEnabled, setWatermarkEnabled] = useState(false);
@@ -8,11 +8,13 @@ export function useWatermarkSettings() {
   useEffect(() => {
     const fetchSettings = async () => {
       try {
-        const settings = await settingsService.getSettingsByType('branding');
+        // Use public settings endpoint that doesn't require authentication
-        const brandingSettings = settingsService.formatBrandingSettings(settings);
+        const response = await api.get('/public/settings');
-        setWatermarkEnabled(brandingSettings.watermark_enabled);
+        setWatermarkEnabled(response.data.branding_watermark_enabled || false);
       } catch (error) {
         console.error('Failed to fetch watermark settings:', error);
+        // Default to false if we can't fetch settings
+        setWatermarkEnabled(false);
       } finally {
         setLoading(false);
       }