Implement iOS state management (AppState + ManifestStore)

[2witstudios]

Epic 6: iOS App — State & Views — Issue 1/5

Source: 1-agent worktree — better separation of concerns with ManifestStore

Description

App-level state management with separate manifest caching.

Acceptance Criteria

• AppState.swift — @Observable, manages connections list, active connection, REST/WS lifecycle
• ManifestStore.swift — separate manifest cache, refresh logic, incremental status updates from WebSocket
• UserDefaults-backed connection persistence
• Auto-connect to last-used server on app launch
• Connection switching (disconnect current, connect to new)
• Error state management with user-facing messages

Dependencies

• Requires: Implement REST client (PPGClient) #78 (PPGClient), Implement WebSocket manager #79 (WebSocketManager)

Files to Create

• ios/PPGMobile/PPGMobile/State/AppState.swift (new)
• ios/PPGMobile/PPGMobile/State/ManifestStore.swift (new)