Device-specific Apple app size analysis

Once can now produce ad-hoc signed app archives for one Apple device model at a time with apple_thinned_package. Keeping each model in its own target makes the variants independently cacheable and ready for size-analysis services such as Sentry without the noise of a universal build.

The target validates device builds, uses Xcode's thinning tool, re-signs embedded bundles, and writes a deterministic archive plus a stable manifest. Existing apple_application bundles now include the supported-platform metadata that Xcode requires for thinning.