Design: profile updates as part of release pipelines

Design the integration between SKU/host release pipelines and the CLI
profiles. Today profile updates are manual; we want a release of (e.g.)
the Flex host to automatically refresh the Flex profile to the new host
version. Output is a written design plus follow-up issues for each
pipeline change.

## Definition of Done

- [ ] Design doc landed in `docs/proposed/` covering: triggers (what
release events update which profiles), publishing flow (who builds
the profile, who signs, who pushes to CDN), versioning, rollback,
and validation gates.
- [ ] Per-SKU contract documented (Flex, Consumption, App Service, etc.)
including which fields update and which stay pinned.
- [ ] Follow-up issues opened for each pipeline change the design
surfaces.
- [ ] Doc reviewed by host team + release pipeline owners.