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/Sync/DuplicateCleanup.swift

@@ -82,7 +82,7 @@ enum DuplicateCleanupPlanner {
         var name: String
         var sets: Int
         var reps: Int
-        var weight: Int
+        var weight: Double
         var loadType: Int
         var durationSeconds: Int
         var machineSettings: [MachineSettingFingerprint]?
@@ -156,7 +156,7 @@ enum DuplicateCleanupPlanner {
         var order: Int
         var sets: Int
         var reps: Int
-        var weight: Int
+        var weight: Double
         var loadType: Int
         var durationSeconds: Int
         var status: String