Three slices in one commit since they're tightly coupled (the
M3.5 deletion only makes sense after M3.3 and M3.4):
M3.3 — SxGLView migrated to declarative '#objc_class("SxGLView")':
- '#extends UIView' for the view-hierarchy + responder chain.
- 'layerClass :: *void = objc_getClass("CAEAGLLayer".ptr);' uses
the M2.1(a) class-level constant form. Registered on the
metaclass; UIView's +layerClass override dispatches here so
EAGL gets the right backing layer.
- Six instance methods (sxTick, layoutSubviews, four touch
selectors) forward to existing legacy IMP free functions.
M3.4 — SxMetalView migrated, same shape as SxGLView; differs only
in the 'layerClass' constant returning CAMetalLayer instead of
CAEAGLLayer. The five shared IMPs (sxTick/layoutSubviews/4 touch
handlers) reach the same free functions — they already branch on
plat.gpu_mode for GL-specific renderbuffer code.
M3.5 — uikit_register_classes() and the two helper registration
functions are deleted outright. Every sx-defined Obj-C class in
this module now goes through the compiler's M1.2 / M2.1(a)
synthesis path at module init. The call site inside
UIKitPlatform.init is gone too — just a comment marking the
migration point.
Chess on iOS-sim: board renders, scene-delegate connection still
fires, GL/Metal layer setup intact, touch dispatch routes through
the synthesized IMP trampolines. 183 example tests + zig build
test green.
End of M3. The platform layer's Obj-C-runtime wiring is fully
declarative.
Remaining: M4 (autoreleasepool + ARC ops), M5 (closure↔block),
M6 (auto-import + production hardening). M1.1.b (Class(T)
parameterization + instancetype) is still deferred — none of
the migrated uikit code needed it.