Add meeting start time alignment for Schedule >Meetings

Today, meeting duration and availability are configurable, but users cannot control when meetings begin within that availability. This makes it difficult to intentionally create buffer time between back-to-back meetings (e.g., 45-minute meetings with a 15-minute break).

Researchers have less control over their schedules, especially when they are running back to back interviews in one week. They will likely want built-in recovery time.

Let's add a new radio button selection to the UI, below Interview duration, and label it "Meeting start times"

We should have a tooltip to better explain what this means, something like this: "Control when meetings can begin within your availability. Useful for creating buffer time between meetings."

The options should be:

• Start on the hour (Meetings can begin at: :00)

• Start every 30 minutes (Meetings can begin at: :00, :30)

• Start every 15 minutes (Meetings can begin at: :00, :15, :30, :45)

If we don't think the explainer text next to the options is necessary, a dropdown will do just fine.