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/Splits/SplitListView.swift

@@ -10,12 +10,19 @@
 import SwiftUI
 import SwiftData
 
+/// The Splits library screen, pushed from Settings → Library: a two-column grid of
+/// split tiles. Tapping a tile opens `SplitDetailView`; long-pressing offers Delete
+/// (the sole split-delete affordance); the toolbar's + adds a new split. Starter
+/// splits are seeded automatically on the true first run (`SyncEngine.autoSeedIfEmpty`),
+/// so an empty library just invites creating one.
 struct SplitListView: View {
     @Environment(SyncEngine.self) private var sync
-    @Environment(\.modelContext) private var modelContext
 
     @Query(sort: \Split.order) private var splits: [Split]
 
+    @State private var showingAddSheet = false
+    @State private var splitToDelete: Split?
+
     var body: some View {
         ScrollView {
             LazyVGrid(columns: [GridItem(.flexible()), GridItem(.flexible())], spacing: 16) {
@@ -25,6 +32,13 @@ struct SplitListView: View {
                     } label: {
                         SplitItem(split: split)
                     }
+                    .contextMenu {
+                        Button(role: .destructive) {
+                            splitToDelete = split
+                        } label: {
+                            Label("Delete", systemImage: "trash")
+                        }
+                    }
                 }
             }
             .padding()
@@ -32,20 +46,44 @@ struct SplitListView: View {
         .overlay {
             if splits.isEmpty {
                 ContentUnavailableView(
-                    label: {
-                        Label("No Splits Yet", systemImage: "dumbbell.fill")
-                    },
-                    description: {
-                        Text("Create a split to organize your workout routine.")
-                    },
-                    actions: {
-                        Button("Add Starter Splits") {
-                            Task { await SplitSeeder.seedDefaults(into: modelContext, using: sync) }
-                        }
-                        .buttonStyle(.borderedProminent)
-                    }
+                    "No Splits Yet",
+                    systemImage: "dumbbell.fill",
+                    description: Text("Create a split to organize your workout routine.")
                 )
             }
         }
+        .navigationTitle("Splits")
+        .toolbar {
+            ToolbarItem(placement: .navigationBarTrailing) {
+                Button {
+                    showingAddSheet = true
+                } label: {
+                    Image(systemName: "plus")
+                }
+                .accessibilityLabel("Add Split")
+            }
+        }
+        .sheet(isPresented: $showingAddSheet) {
+            SplitAddEditView(split: nil)
+        }
+        .confirmationDialog(
+            "Delete Split?",
+            isPresented: Binding(
+                get: { splitToDelete != nil },
+                set: { if !$0 { splitToDelete = nil } }
+            ),
+            titleVisibility: .visible,
+            presenting: splitToDelete
+        ) { split in
+            Button("Delete", role: .destructive) {
+                Task { await sync.delete(split: split) }
+                splitToDelete = nil
+            }
+            Button("Cancel", role: .cancel) {
+                splitToDelete = nil
+            }
+        } message: { split in
+            Text("This will permanently delete \"\(split.name)\" and all its exercises. Past workouts are kept.")
+        }
     }
 }