Remove prompts sidebar

[peppescg]

As based on recent @jtenniswood redesign

[jtenniswood]

Designs
https://www.figma.com/design/TtIS3Uk8qBdoNijeezfJYl/Dashboard?node-id=295-59842&t=97f3tMxGfeKjcbsF-11

[alex-mcgovern]

Work on this has progressed — we have changed the backend to aggregate alerts-per-conversation, and made the dashboard conversation-centric.

This is a fairly chunky change to the user experience, so will take some time to land in a good, robust state. We are probably 70-80% of the way there.