Native GPU pipeline: LOD, visibility, stable radix and indirect rendering

[Xget7]

Scope

Native SDK source: GPU LOD, visibility/compaction, stable 32/16-bit radix and indirect Vulkan drawing; shared engine/LOD files, diagnostics, loaded/drawn HUD, concise contracts and agent harness.
Metal source matches the separately published iOS alpha.2 integration.
No scenes, private notes or signing material are included; source-manifest.json records the export.

Evidence

• Android AAR/APK build, 5 Kotlin decoder tests and 11 harness tests pass.
• An isolated Android host builds a minified release APK against the CI AAR, without the SDK source module.
• Android 16 arm64 emulator through gfxstream/MoltenVK on Apple M4 Pro: 128 stable-sort cases through 3M elements pass; GPU LOD/visibility/radix/indirect chain, visibility and shader-free upload-pressure probes pass (native validation layers unavailable).
• Kitchen 500k loads and renders with app validation layers enabled, no captured Vulkan validation errors, and live loaded/drawn counts.
• Rebinding resources/constants after every radix pipeline transition fixes a reproduced integrated-chain failure on MoltenVK; regression test included.
• SwiftShader passes smaller suites but its large mapped-buffer upload crashes before shaders, also reproduced with raw Vulkan independently of this SDK.

Release boundary

Prepares Android alpha05; merge requires all hosted checks green.
Physical Android quality/performance, Android hybrid compute tiles and RN GPU options remain pending.
Emulator/Mac timings are not phone benchmarks; 16-bit ordering/subpixel/LOD are approximations.
C++ lint findings are corrected without disabling repository checks; two negative enum-validation tests have narrow analyzer suppressions for legal fixed-underlying-type values.
Removed nine obsolete Android engine copies replaced by the shared engine; package paths now match the export manifest. CI explicitly uses NDK 27.1.12297006.
Hosted CI and physical-device acceptance are separate gates.