AB#280444 - Add GamifyWidget SDK module

[dmytro-b-optimove]

Summary

• Adds GamifyWidgetSDK — public entry point with initialize(widgetUrl:) and open(from:userId:token:) that presents a modal sheet
• Adds GamifyWidgetViewController — internal UIKit view controller hosting a WKWebView with JS bridge (READY → INIT → CLOSE handshake), loading spinner, and error state
• Adds GamifyWidgetSDKTests — unit tests for URL initialisation

iOS equivalent of Android SDK PR #91 (AB#280444). No changes to Package.swift — new files sit inside the existing OptimoveSDK target source path.

JS Bridge

Widget fires READY → native responds with INIT (userId/token) via window.postMessage. Widget calls window.webkit.messageHandlers.nativeBridge.postMessage to close. Token is redacted in logs.

Test plan

• cmd+U on OptimoveSDK scheme — GamifyWidgetSDKTests pass
• cmd+B on iOS scheme — clean build, no errors or warnings
• Run QA app, navigate to Gamify Widget, fill tenant + userId, tap Open Widget — sheet opens and close button dismisses