[rinov]

The example still used the legacy application lifecycle. This change adds a scene configuration and SceneDelegate while retaining iOS 13 support, with a launch test that verifies window creation.

• Add SwiftPM regression tests for the existing request format, exhaustive switches over public error enums, and bundled HTML and privacy manifest resources.
• Configure the previously empty example test target so its tests can run.
• Test the package and example through a shared script and add CI coverage for Xcode 26 and 27.
• Limit deployment-target overrides for newer SDKs to CI verification builds. Keep iOS 13 support in SwiftPM and CocoaPods, and retain Swift 5 as the default language mode.

Validation: All three package tests and the example launch test passed locally with Xcode 26.4.1 on the iOS 26.4 Simulator. CI also passed on Xcode 26 and 27. YouTube playback on a physical device has not been verified.

Reference: https://developer.apple.com/documentation/uikit/transitioning-to-the-uikit-scene-based-life-cycle

This is the first compatibility PR. Subsequent PRs use this test infrastructure.