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.

CHANGELOG.md

@@ -0,0 +1,20 @@
+# Changelog
+
+All notable changes to this project are documented here.
+
+## June 2026
+
+- **2.0** — Re-platformed persistence onto an iCloud Drive document architecture:
+  JSON files in iCloud Drive are now the sole source of truth, with a rebuildable
+  SwiftData cache populated by an `NSMetadataQuery` observer. Removed
+  CloudKit/`NSPersistentCloudKitContainer` and the App-Group store.
+- Rebuilt the Apple Watch sync on a new WatchConnectivity bridge keyed by stable
+  ULIDs (the phone is the sole writer of iCloud Drive).
+- Migrated the project to XcodeGen; iOS 26 / watchOS 26, Swift 6 strict
+  concurrency.
+- Splits ship as on-demand starter data generated from the bundled exercise
+  catalogs.
+- Stored exercise/log durations as integer seconds (was a `Date` epoch hack).
+- Fixed: workout marked complete on creation, an undismissable delete dialog,
+  toolbar buttons hidden by nested navigation stacks, and a placeholder
+  "Settings coming soon" row.