[Kyle-Ye]

Summary

• Add a CoreMaterial SwiftPM product with typed recipes, visual styles, dictionary options, and the material dictionary factory.
• Package complete TBD export sets for five supported slices and preserve Objective-C ivar exports during device stub generation.
• Add CoreMaterialExample to inspect material dictionaries and a workflow that builds all five platform targets.

Validation

Local CoreMaterialExample builds pass for iOS, iOS Simulator, macOS, visionOS, and visionOS Simulator. Export coverage, generated artifact consistency, shell syntax, and workflow lint checks pass.