Workouts 2.0: re-base persistence on iCloud Drive documents

Replace Core Data + NSPersistentCloudKitContainer + App-Group store +
WatchConnectivity dictionary sync with the QuickRabbit iCloud-documents
architecture:

- iCloud Drive JSON documents are the sole source of truth (one file per
  aggregate: Splits/<ULID>.json, Workouts/YYYY/MM/<ULID>.json), with a
  rebuildable SwiftData cache populated only by an NSMetadataQuery observer
  and a connect-time reconcile. Soft-delete tombstones; hard iCloud gate.
- Shared model layer (ULID, Codable *Documents + stateless mappers, @Model
  cache entities, SwiftData container) compiled into both targets.
- New iPhone<->Watch bridge over WatchConnectivity keyed by ULIDs; the phone
  is the sole writer of iCloud Drive, the watch round-trips documents.
- AppServices DI + iCloud-required root gate; Swift 6 strict concurrency.
- Starter splits generated on demand from the bundled YAML catalogs.
- Migrate to XcodeGen (project.yml), iOS 26 / watchOS 26; CloudDocuments
  entitlement (drop CloudKit/App Group/aps-environment).
- Duration stored as Int seconds (was a Date epoch hack); fix workout
  end-on-create, undismissable delete dialog, toolbar-hiding nav stacks,
  and the Settings placeholder.
- Add README/CHANGELOG/LICENSE, .gitignore, refreshed REQUIREMENTS, and the
  Scripts/ TestFlight pipeline (release.sh + ASC API scripts).

MARKETING_VERSION 2.0.

Workouts/Views/Splits/SplitAddEditView.swift

@@ -8,10 +8,11 @@
 //
 
 import SwiftUI
-import CoreData
+import SwiftData
 
 struct SplitAddEditView: View {
-    @Environment(\.managedObjectContext) private var viewContext
+    @Environment(SyncEngine.self) private var sync
+    @Environment(\.modelContext) private var modelContext
     @Environment(\.dismiss) private var dismiss
 
     let split: Split?
@@ -23,8 +24,6 @@ struct SplitAddEditView: View {
     @State private var showingIconPicker: Bool = false
     @State private var showingDeleteConfirmation: Bool = false
 
-    private let availableColors = ["red", "orange", "yellow", "green", "mint", "teal", "cyan", "blue", "indigo", "purple", "pink", "brown"]
-
     var isEditing: Bool { split != nil }
 
     init(split: Split?, onDelete: (() -> Void)? = nil) {
@@ -117,8 +116,9 @@ struct SplitAddEditView: View {
             ) {
                 Button("Delete", role: .destructive) {
                     if let split = split {
-                        viewContext.delete(split)
-                        try? viewContext.save()
+                        Task {
+                            await sync.delete(split: split)
+                        }
                         dismiss()
                         onDelete?()
                     }
@@ -131,18 +131,28 @@ struct SplitAddEditView: View {
 
     private func save() {
         if let split = split {
-            // Update existing
-            split.name = name
-            split.color = color
-            split.systemImage = systemImage
+            // Update existing split
+            var doc = SplitDocument(from: split)
+            doc.name = name
+            doc.color = color
+            doc.systemImage = systemImage
+            doc.updatedAt = Date()
+            Task { await sync.save(split: doc) }
         } else {
-            // Create new
-            let newSplit = Split(context: viewContext)
-            newSplit.name = name
-            newSplit.color = color
-            newSplit.systemImage = systemImage
-            newSplit.order = 0
+            // Create new split
+            let existing = (try? modelContext.fetch(FetchDescriptor<Split>())) ?? []
+            let doc = SplitDocument(
+                schemaVersion: SplitDocument.currentSchema,
+                id: ULID.make(),
+                name: name,
+                color: color,
+                systemImage: systemImage,
+                order: existing.count,
+                createdAt: Date(),
+                updatedAt: Date(),
+                exercises: []
+            )
+            Task { await sync.save(split: doc) }
         }
-        try? viewContext.save()
     }
 }