Regex validation

Steps can use a regular expression for auto-validation instead of plain string matching.

To add a regex pattern:
1. Edit a runbook → open a step
2. Fill in the "Validation Regex" field (e.g. \bRunning\b or ^SUCCESS)
3. If the pattern is valid, a green "Valid regex" indicator appears

How it works:
• When a customer submits output, Turtini tests it against the regex
• If the regex matches, the step auto-passes; otherwise it auto-fails
• If a regex is set, it takes precedence over the plain "Expected Output" field
• If the regex field is blank, Turtini falls back to the plain substring match

Tip: use https://regex101.com to test your pattern before saving.