Fix iOS 26 deprecations in SignUpDemo + bulk copyright update

[Sajjon]

Summary

The example app surfaced three iOS 26 deprecation warnings in Xcode 17:

• 'UIRequiresFullScreen' has been deprecated starting in iOS 26.0…
• 'init(frame:)' was deprecated in iOS 26.0: Use init(windowScene:) instead.
• 'main' was deprecated in iOS 26.0: Use a UIScreen instance found through context instead.

All three traced to the pre-iOS-13-style @main-on-AppDelegate shortcut the example used. Migrated to scene-based lifecycle:

What changed

• New SceneDelegate.swift — owns the UIWindow setup. Builds the window via UIWindow(windowScene:) (the modern initialiser); no UIScreen.main access; no init(frame:).
• AppDelegate.swift shrunk to a single method (application(_:configurationForConnecting:options:)) that points the system at the scene config registered in Info.plist. No more direct window setup, no more direct coordinator wiring.
• project.yml — drops the deprecated INFOPLIST_KEY_UIRequiresFullScreen: "YES" and adds an inline UIApplicationSceneManifest pointing at the new SceneDelegate. info.path: Generated.plist lets XcodeGen merge the manifest into the auto-generated plist; the resulting Generated.plist is gitignored alongside the existing .xcodeproj ignore.

Bulk copyright update

Open Zesame → Alexander Cyon (github.com/sajjon) across 84 source / test / markdown files. The LICENSE file's mention of Open Zesame stays — it's the historical attribution about the code's origin in the Zhip wallet, which is factually correct.

Test plan

• just example-gen && just example-build — Build Succeeded, zero deprecation warnings
• just test — all 75 tests pass
• swiftformat --lint + swiftlint --strict (via pre-commit + pre-push hooks) — clean
• just example-run on iPhone 17 / iOS 26.1 simulator — confirm the demo still launches and the SignUp → Home flow still works end-to-end

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.77%. Comparing base (9cda1ec) to head (6f1c4ac).

Additional details and impacted files

@@           Coverage Diff           @@
##             main       #6   +/-   ##
=======================================
  Coverage   87.77%   87.77%           
=======================================
  Files          30       30           
  Lines        1562     1562           
=======================================
  Hits         1371     1371           
  Misses        191      191           

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