fix: prevent photo corruption during upload and add batch processing improvements

- Remove async functions from multer callbacks (primary corruption cause)
- Implement temp directory upload approach with proper cleanup
- Add comprehensive file integrity validation before processing
- Fix batch upload category assignment and photo naming
- Add automatic cleanup service for orphaned temp uploads
- Enhance error handling with better corruption detection
- Add fix-temp-photos script to repair existing temporary files
- Update file watcher to ignore temp upload files

Fixes issues with:
- Corrupted photos showing only partial images
- Photos retaining temp_ names after upload
- Category assignments lost during batch uploads
- Incomplete file uploads causing "Premature end of input" errors

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

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

backend/src/utils/cleanupTempUploads.js

@@ -0,0 +1,78 @@
+const path = require('path');
+const fs = require('fs').promises;
+const logger = require('./logger');
+
+const getStoragePath = () => process.env.STORAGE_PATH || path.join(__dirname, '../../../storage');
+
+/**
+ * Clean up old temporary upload directories
+ * Removes temp directories older than 1 hour
+ */
+async function cleanupTempUploads() {
+  const tempPath = path.join(getStoragePath(), 'temp');
+  
+  try {
+    // Ensure temp directory exists
+    await fs.mkdir(tempPath, { recursive: true });
+    
+    // Read all items in temp directory
+    const items = await fs.readdir(tempPath);
+    
+    let cleanedCount = 0;
+    const oneHourAgo = Date.now() - (60 * 60 * 1000); // 1 hour
+    
+    for (const item of items) {
+      const itemPath = path.join(tempPath, item);
+      
+      try {
+        const stats = await fs.stat(itemPath);
+        
+        // Only process directories that match our upload pattern
+        if (stats.isDirectory() && item.startsWith('upload_')) {
+          // Extract timestamp from directory name
+          const parts = item.split('_');
+          if (parts.length >= 2) {
+            const timestamp = parseInt(parts[1]);
+            
+            // Remove if older than 1 hour
+            if (!isNaN(timestamp) && timestamp < oneHourAgo) {
+              logger.info(`Cleaning up old temp upload directory: ${item}`);
+              await fs.rm(itemPath, { recursive: true, force: true });
+              cleanedCount++;
+            }
+          }
+        }
+      } catch (error) {
+        logger.error(`Error processing temp item ${item}:`, error.message);
+      }
+    }
+    
+    if (cleanedCount > 0) {
+      logger.info(`Cleaned up ${cleanedCount} old temp upload directories`);
+    }
+    
+  } catch (error) {
+    logger.error('Error during temp upload cleanup:', error);
+  }
+}
+
+/**
+ * Start periodic cleanup of temp uploads
+ * Runs every hour
+ */
+function startTempUploadCleanup() {
+  // Run immediately on startup
+  cleanupTempUploads();
+  
+  // Then run every hour
+  setInterval(() => {
+    cleanupTempUploads();
+  }, 60 * 60 * 1000); // 1 hour
+  
+  logger.info('Temp upload cleanup service started');
+}
+
+module.exports = {
+  cleanupTempUploads,
+  startTempUploadCleanup
+};