Automated PR created by Copilot: adds implementation and tests for specs/264 cross-tenant promotion execution. Co-authored-by: Ahmed Darrazi <ahmed.darrazi@live.de> Reviewed-on: #320
Implements platform feature branch `feat/043-cross-tenant-compare-and-promotion`. Target branch: `platform-dev`. Follow-up integration path after merge: `platform-dev` → `dev`. Co-authored-by: Ahmed Darrazi <ahmed.darrazi@live.de> Reviewed-on: #307
