Add database migrations and user creation

start.sh

@@ -1,5 +1,18 @@
 #!/bin/bash
 
+# Initialize database (run migrations)
+echo "Running database migrations..."
+python -m argilla_server database migrate
+
+# Create default user if USERNAME and PASSWORD are set
+if [ -n "$USERNAME" ] && [ -n "$PASSWORD" ]; then
+    echo "Creating admin user..."
+    python -m argilla_server database users create \
+        --username "$USERNAME" \
+        --password "$PASSWORD" \
+        --role owner || echo "User may already exist, continuing..."
+fi
+
 # Start backup script in background (only if HF_TOKEN is set)
 if [ -n "$HF_TOKEN" ]; then
     python /app/backup_to_hub.py &