Sub-step 1 Prompt: Build the workout plan creation flow: users can create a plan with a name and a description.

Sub-step 2 Prompt: Search/add exercises from the library into it via plan_exercises, set target sets/reps/weight per exercise, and reorder exercises via drag-and-drop.

Sub-step 3 Prompt:  Include edit and delete for existing plans. Build ability for people to share workouts with friends.