Missing JsModule qualifier on a global level

This strikingly simple minimal example:
```typescript
export declare function ping();
```

is converted to:
```kotlin
external fun ping()
```

This is unusable since JsModule annotation is missing.

Start by reproducing the minimal TypeScript declaration `export declare function ping();` and tracing the conversion to the generated Kotlin `external fun ping()`. The change is complete when the generated top-level declaration includes the required JsModule annotation and the original example is covered by a regression test.

Written by the indexing model from the issue text.