Third Phase 1D cluster. `UIScreen.mainScreen.nativeScale` chain reads through `#objc_call(*void)` + `#objc_call(f64)`. First standalone `#objc_call(f64)` exercise — `f64` returns had only been covered indirectly by the 4×f64 UIEdgeInsets HFA path. Net -4 lines. iOS-sim chess regression smoke: sharp text rendering + accurate touch hit-testing both confirm `plat.dpi_scale` is being populated correctly through the new path.