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/Views/WorkoutLogs/WeightProgressionChartView.swift

@@ -34,7 +34,12 @@ struct WeightProgressionChartView: View {
     @AppStorage("weightUnit") private var weightUnit: WeightUnit = .lb
 
     private var weightData: [WeightDataPoint] {
-        logs.map { WeightDataPoint(date: $0.date, weight: $0.weight) }
+        // Top-set *actual* weight per completed log; legacy logs without recorded
+        // entries fall back to the planned weight (the old behavior).
+        logs.map { log in
+            let topSet = log.setEntries?.compactMap(\.weight).max()
+            return WeightDataPoint(date: log.date, weight: topSet ?? log.weight)
+        }
     }
 
     var body: some View {
@@ -100,7 +105,7 @@ struct WeightProgressionChartView: View {
 
         if weightDifference > 0 {
             let percentIncrease = firstWeight > 0
-                ? Int((Double(weightDifference) / Double(firstWeight)) * 100)
+                ? Int((weightDifference / firstWeight) * 100)
                 : 0
             if percentIncrease >= 20 {
                 return "Amazing progress! You've increased your weight by \(weightUnit.format(weightDifference)) (\(percentIncrease)%)!"
@@ -121,5 +126,5 @@ struct WeightProgressionChartView: View {
 struct WeightDataPoint: Identifiable {
     let id = UUID()
     let date: Date
-    let weight: Int
+    let weight: Double
 }