v2-platform: 06 Zephyr removal across all workspaces + provider seam

Parent

#274 (v2 platform services spec)

What to build

Zephyr removal: the CDN bundler plugin comes out of every workspace build config, the deploy-output parsing and ZE-error classification come out of the build orchestration, and the catalog pins are dropped. The provider seam (the storage adapter from the core ticket) is formalized as the extension point for future providers (IPFS notably). Official CI deploys through the deploy service under the platform account on the official domain. After this ticket, nothing in the platform references Zephyr and the official production path is the new one end-to-end.

Acceptance criteria

• No workspace build config contains a CDN bundler plugin; builds produce plain dist output
• Build orchestration no longer parses deploy-console output or retries on CDN-provider errors
• Official CI (build → upload via deploy service → publish) succeeds end-to-end on the official domain
• The provider seam is documented as the extension point, with the local-disk and S3 providers as reference implementations
• A full official deploy (all workspaces) completes with zero Zephyr involvement anywhere
• Rollback story: the previous official URLs remain valid (immutable content-hash storage)

Blocked by

• #278 (bos deploy CLI)
• #279 (R2/S3 storage provider)

Start by tracing the workspace build configs, build orchestration, official CI path, deploy service, and provider seam described in the ticket. Check the blocked #278 and #279 work first, then verify plain dist output, provider documentation with local-disk and S3 references, and an end-to-end official deploy with rollback URLs and no Zephyr involvement.