Enhancement: Activation Scheduling

I see that you can customize the delay time from the default 30s, but it could be helpful to schedule activation to start at a given time every day (when your office closes, etc).

Start by tracing how Haven currently handles the configurable activation delay in the Android app. Define the expected behavior for a daily activation time, including what happens across restarts and time changes. Done means activation can be scheduled for a chosen time each day and the behavior is covered by appropriate checks.

Written by the indexing model from the issue text.