Invitation status, resend, and publish confirmation

What changed

• The candidates table now shows when an invitation failed to send or has expired. A Resend button sends that one candidate a fresh link.
• Publishing an assessment now asks you to confirm first and lists what gets locked, such as the questions and time limit. The title, description, and invite settings stay editable afterward.
• A team member who opens their company's assessment link while signed in no longer starts a real candidate session. Turning off question randomization now keeps each question you picked as its own slot.