A Program tab on every client

Each client now has a Program tab in their detail page:

• The whole plan at a glance. A week timeline shows the client's current week, what's done, what's ahead, deloads flagged, and how many sessions each week holds.
• Browse any week. Step through the weeks to review the sessions scheduled in each.
• Set where they are. Move the client's current week with one tap — it updates instantly on their side too.

Editing sessions and exercises still happens in the program builder; in-place editing from this tab is coming next.