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.

Shared/Utils/Date+Extensions.swift

@@ -0,0 +1,40 @@
+import Foundation
+
+extension Date {
+    // Cached formatters — DateFormatter init is expensive and these are called
+    // in list rows on every render pass.
+    private static let shortDateTime: DateFormatter = {
+        let f = DateFormatter(); f.dateStyle = .short; f.timeStyle = .short; return f
+    }()
+    private static let timeOnly: DateFormatter = {
+        let f = DateFormatter(); f.dateStyle = .none; f.timeStyle = .short; return f
+    }()
+    private static let mediumDate: DateFormatter = {
+        let f = DateFormatter(); f.dateStyle = .medium; f.timeStyle = .none; return f
+    }()
+    private static let monthAbbrev: DateFormatter = {
+        let f = DateFormatter(); f.dateFormat = "MMM"; return f
+    }()
+    private static let weekdayAbbrev: DateFormatter = {
+        let f = DateFormatter(); f.dateFormat = "EEE"; return f
+    }()
+
+    func formattedDate() -> String { Self.shortDateTime.string(from: self) }
+    func formattedTime() -> String { Self.timeOnly.string(from: self) }
+    func formatDate() -> String { Self.mediumDate.string(from: self) }
+
+    func isSameDay(as other: Date) -> Bool {
+        Calendar.current.isDate(self, inSameDayAs: other)
+    }
+
+    var abbreviatedMonth: String { Self.monthAbbrev.string(from: self) }
+    var abbreviatedWeekday: String { Self.weekdayAbbrev.string(from: self) }
+    var dayOfMonth: Int { Calendar.current.component(.day, from: self) }
+
+    func humanTimeInterval(to other: Date) -> String {
+        let interval = other.timeIntervalSince(self)
+        let hours = Int(interval) / 3600
+        let minutes = (Int(interval) % 3600) / 60
+        return hours > 0 ? "\(hours)h \(minutes)m" : "\(minutes)m"
+    }
+}