OpenConceptLab/ocl_issues#2480 | clone operation everything or nothing

[snyaggarwal]

Linked Issue

Closes OpenConceptLab/ocl_issues#2480

[paynejd]

Flagging a regression risk spotted during review:

This PR adds except CloneError handling to SourceConceptsCloneView.post in core/sources/views.py (L400-402), but ConceptCloneView.post in core/concepts/views.py (L471-474) also calls Bundle.clone(...) and doesn't catch CloneError.

Before this PR, a failed clone through that endpoint silently succeeded. After this PR, it will raise an uncaught CloneError and surface as HTTP 500 — a behavioral regression on that entry point.

Suggest mirroring the same try/except CloneError block so both $clone entry points return the structured 400 response consistently.