* Separate native linking from C compilation
- Split the helper-object runtime-pack path into explicit link planning and platform linking.
- Reserve SCRIPTC_LINKER for object-only executable links while retaining a deprecated SCRIPTC_CC compatibility path.
- Add no-legacy-C coverage and document the linker/SDK boundary.
* Preserve runtime pack link errors
* Fix linker cache invalidation and warnings
* Fix C executable cache routing
- Keep explicit C builds on compiler-backed cache identities.
- Cover linker-only environment changes across exact C repeats.