docs(ios): update roadmap Phase 3 Week 6 with iOS app foundation progress
- Xcode project setup: ✅ (XcodeGen, iOS 17+, zero third-party deps)
- Timer engine Swift port: ✅ (TimerEngine, Cascade, Urgency, Format, TimeBlindness)
- Data models: ✅ partial (CMTimer Codable struct, UserDefaults persistence)
- iOS screens: ✅ (Timeline, CreateTimer, Pomodoro, History, Settings, AlarmOverlay)
- Notification scheduling: ✅ (UNUserNotificationCenter, cascade warnings, actions)
- Haptic engine: ✅ (urgency-mapped feedback patterns)
- XCTest: 58 tests passing (TimerEngine, Cascade, Format)
- Remaining: Recurrence, NLParser, ContextMessages (Phase 2 web deps), SwiftData migration
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