fix: DatabaseManager removes inline comments correctly in migrations

- Fixed SQL statement parsing to remove both line and inline comments
- Prevents incomplete SQL statements from inline comments
- Migration 005 and 006 now apply correctly via automatic migration system
- Tested with production data: All 72 groups have display_in_workshop = 0 (GDPR compliant)

backend/src/database/DatabaseManager.js

@@ -361,11 +361,24 @@ class DatabaseManager {
                     // Execute migration in a transaction
                     await this.run('BEGIN TRANSACTION');
                     
+                    // Remove comments (both line and inline) before splitting
+                    const cleanedSql = sql
+                        .split('\n')
+                        .map(line => {
+                            // Remove inline comments (everything after --)
+                            const commentIndex = line.indexOf('--');
+                            if (commentIndex !== -1) {
+                                return line.substring(0, commentIndex);
+                            }
+                            return line;
+                        })
+                        .join('\n');
+                    
                     // Split by semicolon and execute each statement
-                    const statements = sql
+                    const statements = cleanedSql
                         .split(';')
                         .map(s => s.trim())
-                        .filter(s => s.length > 0 && !s.startsWith('--'));
+                        .filter(s => s.length > 0);
                     
                     for (const statement of statements) {
                         await this.run(statement);