Add: add_user script

Run `add_user.sh` in the extra/ directory to manually add an admin user.

extra/add_user.sh

@@ -0,0 +1,16 @@
+#!/bin/bash
+read -p "Username: " username
+read -sp "Password: " password
+echo
+
+hash=$(python3 -c "
+from werkzeug.security import generate_password_hash;
+print(generate_password_hash('$password'))
+")
+
+mysql -uassetadmin -p1234 asset_test_db <<EOF
+INSERT INTO users (username, password_hash) 
+VALUES ('$username', '$hash');
+EOF
+
+echo "User $username added successfully"