[GLM 5.3 Flash] Preserve original names when saving text checkpoints (#48676)
[GLM5 Next] Preserve original text checkpoint names
Register the GLM5 Next conversion mapping for the standalone text model type.
This keeps saved checkpoints compatible with the released tensor layout.
Add regression coverage for mHC, KDA, and routed expert keys.
Signed-off-by: Shijin Zhang <75300765+Dovis01@users.noreply.github.com>