Catalog & client detail — connected to real data

A pass to make the coach surfaces reflect real data instead of prototype mock-ups:

• Catalog edits persist. Clicking a service or offer now opens it pre-filled with its real values and saves your changes to the database (previously a row click opened a blank "Add" form). Create, edit, and delete all write through.
• Client nutrition is real. A client's Overview tab now shows the actual nutrition plan assigned to them (from Coaching → Nutrition), with a link to manage it — no more disconnected placeholder meal plans.
• Coupons tab removed. It was a non-functional placeholder that lost its data on refresh. It's gone until discount codes are built for real.