Extension runtime

The MdWrk extension runtime gives package authors a governed way to extend the workspace. Instead of patching the client directly, extensions describe their contribution through documented package and manifest surfaces.

This matters for trust and portability. Runtime lifecycle, compatibility metadata, installable artifacts, and host context stay explicit, which makes extension behavior easier to inspect and easier to verify.

The reusable lander package does not contain any MdWrk extension claim. MdWrk-specific extension facts live here in the content pack, while the lander packages render feature pages generically.