Fix gallery login errors and photo upload issues

- Fix photo upload cross-device link error
  - Changed fs.rename to fs.copyFile + fs.unlink to handle Docker volume mounts
  - This fixes EXDEV errors when uploading photos from /tmp to storage

- Improve gallery login error handling
  - Add console logging for debugging
  - Prevent form refresh with stopPropagation
  - Show specific error messages based on status codes
  - Keep password field populated on error for retry
  - Map 404 to gallery not found message

- Enhanced upload error messages
  - Show specific error message for each failed file
  - Display backend error messages in toast notifications

These fixes resolve:
1. Photo uploads failing silently with cross-device link errors
2. Login errors not displaying and form refreshing
3. Upload errors not showing user-friendly messages

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

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

frontend/src/pages/GalleryPage.tsx

@@ -50,6 +50,8 @@ export const GalleryPage: React.FC = () => {
 
   const handleLogin = async (e: React.FormEvent) => {
     e.preventDefault();
+    e.stopPropagation(); // Prevent any bubbling
+    
     if (!password.trim()) {
       setLoginError(t('auth.pleaseEnterPassword'));
       return;
@@ -66,13 +68,17 @@ export const GalleryPage: React.FC = () => {
         success: true
       });
     } catch (error: any) {
+      console.error('Login error:', error);
       const errorMessage = error.response?.data?.error || 'Invalid password';
+      const statusCode = error.response?.status;
       
       // Map backend error messages to user-friendly translations
-      if (errorMessage.toLowerCase().includes('invalid password')) {
+      if (statusCode === 401 || errorMessage.toLowerCase().includes('invalid password')) {
         setLoginError(t('auth.wrongPassword'));
-      } else if (error.response?.status === 429 || errorMessage.toLowerCase().includes('too many')) {
+      } else if (statusCode === 429 || errorMessage.toLowerCase().includes('too many')) {
         setLoginError(t('auth.tooManyAttempts'));
+      } else if (statusCode === 404) {
+        setLoginError(t('errors.galleryNotFound'));
       } else {
         setLoginError(t('auth.invalidPassword'));
       }
@@ -80,8 +86,12 @@ export const GalleryPage: React.FC = () => {
       // Track failed password entry
       analyticsService.trackGalleryEvent('password_entry', {
         gallery: slug,
-        success: false
+        success: false,
+        statusCode
       });
+      
+      // Keep the password field to allow retry
+      // Do not clear the password
     } finally {
       setIsLoggingIn(false);
     }