Record per-set actuals and drive the chart and volume from them

Every completed set now writes a SetEntry (reps/weight or seconds),
pre-filled from the plan by transition(to:) so the list checkbox, both
run flows, and One More all capture for free; reset clears, skip keeps
partials. The rest and finish pages show the just-done set as a pill
that opens a stepper sheet for correcting reps and weight (2.5 lb /
1.25 kg steps). The Weight Progression chart plots the top-set actual
weight and workout volume sums recorded sets, both falling back to the
plan for legacy logs via effectiveSetEntries.

Storage side of UX #3 rides along: plan weights are Double now.
Schema bumps: SplitDocument 2→3, WorkoutDocument 3→4 (a fractional
weight fails an older Int decode, and a rewrite would strip the
irreplaceable actuals), SwiftData cache 4→5. A per-log updatedAt is
reserved for the future cross-device log merge.

Claude-Session: https://claude.ai/code/session_01HJDQQDA9QdP8zByg43H5v3

Workouts Watch App/Views/ExerciseProgressView.swift

@@ -491,6 +491,9 @@ struct ExerciseProgressView: View {
         if let i = doc.logs.firstIndex(where: { $0.id == logID }) {
             doc.logs[i].sets = newCount
             doc.logs[i].currentStateIndex = newCount - 1   // every prior set is now complete
+            // The old final set just became a completed *prior* set — record its entry.
+            // The bonus set's own entry lands when it completes, not now.
+            doc.logs[i].fillSetEntries(upTo: newCount - 1, at: Date())
             doc.logs[i].transition(to: .inProgress)
             recomputeWorkoutStatus()
             doc.updatedAt = Date()
@@ -518,6 +521,9 @@ struct ExerciseProgressView: View {
         guard reached > doc.logs[i].currentStateIndex else { return }
 
         doc.logs[i].currentStateIndex = reached
+        // Log-by-default: each newly-completed set gets a plan-filled entry
+        // (append-only; adjustments happen on the phone — no watch adjust UI in v1).
+        doc.logs[i].fillSetEntries(upTo: reached, at: Date())
         doc.logs[i].transition(to: .inProgress)
 
         recomputeWorkoutStatus()