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 AppTests/WatchCacheApplierTests.swift

@@ -151,6 +151,30 @@ struct WatchCacheApplierTests {
         #expect(workoutIDs(in: ctx) == ["01WKA"])
     }
 
+    // MARK: - New-field fidelity through the watch cache
+
+    /// A pushed workout carrying the v4 log fields — fractional weight, recorded
+    /// `setEntries`, per-log `updatedAt` — survives apply → cache entity → document
+    /// intact, so the watch's echo back to the phone can't strip actuals.
+    @Test func applyRoundTripsSetEntriesAndPerLogUpdatedAt() throws {
+        let ctx = try makeContext()
+        var doc = workout(id: "01WKENTRIES")
+        doc.logs[0].weight = 42.5
+        doc.logs[0].status = WorkoutStatus.completed.rawValue
+        doc.logs[0].setEntries = [
+            SetEntry(reps: 10, weight: 42.5, completedAt: Self.ts),
+            SetEntry(reps: 8, weight: 45, completedAt: Self.ts),
+        ]
+        doc.logs[0].updatedAt = Self.ts
+
+        WatchCacheApplier.apply(splits: [], workouts: [doc], into: ctx)
+        let entity = try #require(CacheMapper.fetchWorkout(id: "01WKENTRIES", in: ctx))
+        let rebuilt = WorkoutDocument(from: entity)
+        #expect(rebuilt.logs[0].weight == 42.5)
+        #expect(rebuilt.logs[0].setEntries == doc.logs[0].setEntries)
+        #expect(rebuilt.logs[0].updatedAt == Self.ts)
+    }
+
     @Test func optionalOverloadReturnsTrueWhenBothSetsDecode() throws {
         let ctx = try makeContext()
         // Typed optionals to disambiguate onto the nil-aware overload (an authoritative,