Add an external SKIE or KMP-NativeCoroutines integration fixture

[sonmbol]

Contribute a small compile-tested fixture representing a framework/export configuration that DailyPulse does not cover.

Acceptance criteria:

• identify Kotlin, exporter, Swift, and Xcode versions;
• contain no private application code or credentials;
• verify initial value, later emission, cancellation, rebinding, and ownership;
• keep SKIE and NativeCoroutines symbols isolated to the appropriate product;
• document the exact build command.

A focused fixture is preferred over a second showcase application.