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

Workouts/Screenshots/ScreenshotRootView.swift

@@ -29,8 +29,10 @@ struct ScreenshotRootView: View {
         if let workout = activeWorkout {
             switch ScreenshotSeed.screen(default: "workouts") {
             case "exercise":
-                let logID = WorkoutDocument(from: workout).logs.first { $0.exerciseName == "Bench Press" }?.id
+                let logID = WorkoutDocument(from: workout).logs.first { $0.exerciseName == "Seated Row" }?.id
                 NavigationStack { ExerciseView(workout: workout, logID: logID ?? "") }
+            case "run":
+                ScreenshotRunView(workout: workout)
             case "settings":
                 SettingsView()
             default:
@@ -41,4 +43,26 @@ struct ScreenshotRootView: View {
         }
     }
 }
+
+/// The paged run flow for the in-progress exercise, showing the animated form guide
+/// (with machine props) — the screenshot works off its own local document copy, so
+/// nothing persists.
+private struct ScreenshotRunView: View {
+    @State private var doc: WorkoutDocument
+    private let logID: String
+
+    init(workout: Workout) {
+        let document = WorkoutDocument(from: workout)
+        _doc = State(initialValue: document)
+        logID = document.logs.first { $0.exerciseName == "Seated Row" }?.id
+            ?? document.logs.first?.id ?? ""
+    }
+
+    var body: some View {
+        NavigationStack {
+            ExerciseProgressView(doc: $doc, logID: logID, onChange: {},
+                                 onLive: { _ in }, onLiveEnded: {}, incomingFrame: nil)
+        }
+    }
+}
 #endif