feat: finish native customization and platform seams

Review threads live on the whole diff, not on one commit, so none are shown here - a thread's line means something in the branch's final form, and painting it into an intermediate step would put it on code it is not about.

packages/zig/test/ios_conformance_test.zigmodified+9-3

Changes to packages/zig/test/ios_conformance_test.zig

		⋯200 linesShow the 200 lines above this hunk@@ -201,10 +201,16 @@ const dispatch_end = "func webView(";
201	201	/// and HKLiveWorkoutBuilder are owned by CraftHealth.swift, including their
202	202	/// delegate callbacks and iOS 26 availability; the actions remain on the
203	203	/// Swift shim until the Zig bridge has an equivalent lifecycle channel.
204		-/// 60 when native screens gained setAppearance and getAppearance. They update
	204	+/// 61 when native screens gained setAppearance and getAppearance. They update
205	205	/// the app-wide UIKit style and remain on the Swift side until Zig owns that
206		-/// lifecycle as well; no existing Zig action was removed.
207		-const max_not_yet_migrated: usize = 60;
	206	+/// lifecycle as well; each new action increases the outstanding count, and no
	207	+/// existing Zig action was removed.
	208	+/// 59 when the spec gained getHealthSamples: glucose, insulin and carbs one
	209	+/// sample at a time (bloodGlucose, insulinDelivery, dietaryCarbohydrates), an
	210	+/// HKSampleQuery in CraftHealth.swift like the other health reads. It went
	211	+/// into Swift first and falls through to the shim, which serves it. Not a
	212	+/// regression: no action left Zig.
	213	+const max_not_yet_migrated: usize = 61;
208	214
209	215	fn dispatcherRegion() []const u8 {
210	216	// CraftApp.swift also contains chrome, console and bridge-relay handlers.