fix: resolve multiple UI issues in admin panel

- Fixed dropdown menu visibility in events table by using fixed positioning
- Fixed double /api prefix in settings upload endpoints (favicon, watermark)
- Fixed thumbnail display in hero image selection by properly handling API paths
- Removed unnecessary console.log statements
- Added proper cleanup for dropdown on scroll/resize events

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

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

frontend/src/services/settings.service.ts

@@ -100,7 +100,7 @@ export const settingsService = {
     formData.append('logo', file);
     
     const response = await api.post<{ logoUrl: string }>(
-      '/api/admin/settings/logo',
+      '/admin/settings/logo',
       formData,
       {
         headers: {
@@ -118,7 +118,7 @@ export const settingsService = {
     formData.append('favicon', file);
     
     const response = await api.post<{ faviconUrl: string }>(
-      '/api/admin/settings/favicon',
+      '/admin/settings/favicon',
       formData,
       {
         headers: {
@@ -136,7 +136,7 @@ export const settingsService = {
     formData.append('watermarkLogo', file);
     
     const response = await api.post<{ watermarkLogoUrl: string }>(
-      '/api/admin/settings/branding/watermark-logo',
+      '/admin/settings/branding/watermark-logo',
       formData,
       {
         headers: {