Assigning a program now takes a snapshot

Assigning a program to a client now creates an independent copy instead of a live link:

• Edit templates freely. Tweaking a library template — reps, exercises, whole days — no longer reaches back and changes programs your clients are already doing. What they see only changes when you assign again.
• Nothing is lost in the copy. The snapshot carries the full plan: rep ranges, load type, RPE/RIR, rest, supersets and interval timing, substitutions, and the week layout.
• Library stays clean. Per-client snapshots don't clutter your program library — you only see your real templates there.