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/Views/WorkoutLogs/WeightProgressionChartView.swift

@@ -20,8 +20,12 @@ struct WeightProgressionChartView: View {
     init(exerciseName: String) {
         self.exerciseName = exerciseName
         let name = exerciseName
+        // `completed` is derived (status == .completed); the predicate compares the
+        // stored `statusRaw` column directly, since #Predicate can't call a computed
+        // property. Capture the raw value in a local so the macro can embed it.
+        let completedRaw = WorkoutStatus.completed.rawValue
         _logs = Query(
-            filter: #Predicate<WorkoutLog> { $0.exerciseName == name && $0.completed },
+            filter: #Predicate<WorkoutLog> { $0.exerciseName == name && $0.statusRaw == completedRaw },
             sort: \WorkoutLog.date,
             order: .forward
         )