The four foreign-class declarations move into a new sub-module
`library/modules/platform/android_jni.sx`, imported under a named
namespace from `android.sx`:
Jni :: #import "modules/platform/android_jni.sx";
This keeps the bare class names (`Activity`, `Window`, `View`,
`WindowInsets`) out of the top level — consumers that flat-import
`modules/platform/android.sx` no longer see `View` collide with
`modules/ui/view.sx`'s protocol of the same name (chess hit this
on the first build attempt).
Compiler-side change: `scanDecls`/`lowerDecls` now also iterate any
`namespace_decl` they encounter and register the contained
`foreign_class_decl`s under their qualified name (`Jni.Activity`).
The recursive scan continues to register the bare names too, so
cross-class refs inside method signatures (e.g. `getWindow ::
(self: *Self) -> *Window`) still resolve through the bare key.
Receiver types like `*Jni.Activity` now route through
`getStructTypeName` → "Jni.Activity" → `foreign_class_map` lookup.
`sx_query_safe_insets_jni`'s param signature changes from
`activity: *Activity` to `activity: *Jni.Activity`; the caller in
`AndroidPlatform.safe_insets` casts via `xx`.
Verified on-device — chess APK built with the new sx, installed via
`adb install -r`, launched on the Pixel. Screencap shows the board
rendering with correct status-bar clearance (time + battery icons
visible above the board, board sized below them) — safe insets are
being queried via the new declarative dispatch and produce the same
values as the pre-migration hand-rolled #jni_call chain.
129/129 examples + cross_compile 3/3 + on-device chess all green.