## Why
`WorkspaceMigrationBuildOrchestratorService.buildWorkspaceMigration` was
1117 lines of 30 near-identical copy-pasted blocks (one per metadata
entity) plus a 165-line ordered `actions: [...]` literal. Adding a new
entity meant copying ~30 lines and hoping the boilerplate stayed in
sync; the actual per-entity execution order was buried in the noise.
## Gain
- Orchestrator: **1117 → 388 lines**
- Net diff: **-558 lines**
- Adding a new entity is now a single line in the registry
- Execution order is visible at a glance
