Add machine comfort settings and tighten the document schemas

Machine-based exercises now carry ordered name/value comfort settings
(seat height, back-rest position, ...) on both ExerciseDocument and, as a
plan-time snapshot, WorkoutLogDocument — the optional array doubles as the
machine flag. Editable from the exercise editor's new Machine section and
from the workout row's settings sheet, whose mid-workout edits write back
to the originating split (workout saved first, so seed clone-on-edit
repointing can't clobber the log edit).

Schema tightening rides the same rev: splits bump to v2 (weight-reminder
fields and the unused exercise category removed), workouts to v3 (the
derived `completed` flag removed; status is the single source). Starter
seeds regenerated at v2 with unchanged ULIDs; SwiftData cache schema
bumped to rebuild. SCHEMA.md documents the shapes.

Claude-Session: https://claude.ai/code/session_01LEoff8bXGBS83tK1c55Mf7

Shared/Model/Entities.swift

@@ -62,15 +62,16 @@ final class Exercise {
     var weight: Int = 0
     var loadType: Int = LoadType.weight.rawValue
     var durationTotalSeconds: Int = 0
-    var weightLastUpdated: Date?
-    var weightReminderTimeIntervalWeeks: Int = 2
-    var categoryRaw: Int = ExerciseCategory.main.rawValue
+    // Machine comfort settings — stored directly as an optional Codable array
+    // (SwiftData persists the `[MachineSetting]` composite), mirroring how
+    // `Workout` stores `hrZoneSeconds` as a plain `[Double]?`. `nil` → not a
+    // machine exercise; empty → a machine exercise with nothing recorded yet.
+    var machineSettings: [MachineSetting]?
 
     var split: Split?
 
     init(id: String, name: String, order: Int, sets: Int, reps: Int, weight: Int,
-         loadType: Int, durationTotalSeconds: Int, weightLastUpdated: Date?,
-         weightReminderTimeIntervalWeeks: Int, categoryRaw: Int = ExerciseCategory.main.rawValue) {
+         loadType: Int, durationTotalSeconds: Int, machineSettings: [MachineSetting]? = nil) {
         self.id = id
         self.name = name
         self.order = order
@@ -79,9 +80,7 @@ final class Exercise {
         self.weight = weight
         self.loadType = loadType
         self.durationTotalSeconds = durationTotalSeconds
-        self.weightLastUpdated = weightLastUpdated
-        self.weightReminderTimeIntervalWeeks = weightReminderTimeIntervalWeeks
-        self.categoryRaw = categoryRaw
+        self.machineSettings = machineSettings
     }
 
     var loadTypeEnum: LoadType {
@@ -89,11 +88,6 @@ final class Exercise {
         set { loadType = newValue.rawValue }
     }
 
-    var categoryEnum: ExerciseCategory {
-        get { ExerciseCategory(rawValue: categoryRaw) ?? .main }
-        set { categoryRaw = newValue.rawValue }
-    }
-
     /// One-line plan summary for list rows — duration exercises show their hold time
     /// ("3 × 45 sec"), unloaded ones drop the weight ("3 × 12 reps"), weighted ones
     /// keep the full "3 × 10 × 40 lb".
@@ -233,16 +227,22 @@ final class WorkoutLog {
     var loadType: Int = LoadType.weight.rawValue
     var durationTotalSeconds: Int = 0
     var currentStateIndex: Int = 0
-    var completed: Bool = false
     var statusRaw: String = WorkoutStatus.notStarted.rawValue
     var notes: String?
     var date: Date = Date()
+    // Snapshot of the exercise's machine comfort settings at plan time — stored
+    // directly as an optional Codable array, same pattern as `Exercise`.
+    var machineSettings: [MachineSetting]?
+    var startedAt: Date?
+    var completedAt: Date?
 
     var workout: Workout?
 
     init(id: String, exerciseName: String, order: Int, sets: Int, reps: Int, weight: Int,
-         loadType: Int, durationTotalSeconds: Int, currentStateIndex: Int, completed: Bool,
-         statusRaw: String, notes: String?, date: Date) {
+         loadType: Int, durationTotalSeconds: Int, currentStateIndex: Int,
+         statusRaw: String, notes: String?, date: Date,
+         machineSettings: [MachineSetting]? = nil,
+         startedAt: Date? = nil, completedAt: Date? = nil) {
         self.id = id
         self.exerciseName = exerciseName
         self.order = order
@@ -252,10 +252,12 @@ final class WorkoutLog {
         self.loadType = loadType
         self.durationTotalSeconds = durationTotalSeconds
         self.currentStateIndex = currentStateIndex
-        self.completed = completed
         self.statusRaw = statusRaw
         self.notes = notes
         self.date = date
+        self.machineSettings = machineSettings
+        self.startedAt = startedAt
+        self.completedAt = completedAt
     }
 
     var status: WorkoutStatus {