Fix backend 500 errors for event creation and system version

- Fix system version endpoint to read package.json using fs instead of require
  - Prevents MODULE_NOT_FOUND error in Docker container
  - Uses path.join to find package.json reliably

- Fix event creation email queue error
  - Change email_type from 'creation' to 'gallery_created' to match template key
  - Update email_data to include all required template variables
  - Added missing created_at and updated_at columns to email_queue table

- Fix file watcher duplicate photo insertion
  - Add check to prevent re-inserting existing photos on backend restart

These fixes resolve:
1. 500 error when accessing /api/admin/system/version
2. 500 error when creating new events
3. Email queue processing errors
4. Photo duplication issue

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

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

backend/src/routes/adminSystem.js

@@ -10,10 +10,18 @@ const router = express.Router();
 router.get('/version', adminAuth, async (req, res) => {
   try {
     // Read backend version from package.json
-    const packageJson = require('../../../package.json');
+    let backendVersion = '1.0.0';
+    try {
+      const packagePath = path.join(__dirname, '../../package.json');
+      const packageContent = await fs.readFile(packagePath, 'utf8');
+      const packageJson = JSON.parse(packageContent);
+      backendVersion = packageJson.version || '1.0.0';
+    } catch (err) {
+      console.error('Could not read package.json:', err);
+    }
     
     res.json({
-      backend: packageJson.version,
+      backend: backendVersion,
       frontend: '1.0.0', // This will be set by frontend
       node: process.version,
       environment: process.env.NODE_ENV || 'production'