[native-split] Add a Function gateway and one Sandbox worker

Following vercel-openclaw#9, this adds the native split implementation: an OpenClaw gateway in a Vercel container Function, with one Sandbox and Drive for native agent execution. Both use OpenClaw 4a6520de4990169a45c6ea2cf64ff0dd44ba8c70. The example includes node enrollment, mandatory worker placement, HTTP/WebSocket forwarding and a two-turn smoke test with independent worker-file and gateway-transcript checks.

Validation: npm test passes 23 tests. A live Redis probe admitted 1 of 8 owners and refused replacement without expiry. The full image built and deployed; protected health/control requests returned 200. The final cloud proof allocated one Sandbox and Drive, and native configuration and identity commands exited 0. Container OIDC wiring and VCR reference comparison bugs found in earlier attempts are fixed and covered by regressions.

Live blocker: the native worker's WebSocket upgrade received HTTP 503 six times. Bootstrap failed before enrollment completed; no model/file turn ran. Later status requests reached an uninitialized controller. Owner routing and gateway-instance lifetime still need qualification; the exact rejection cause is unresolved. Failed resources and logs are preserved. Dated verification.

This is for architecture review. Gateway state is temporary, nonowners return 503, and automatic takeover is disabled. External gateway persistence, reliable owner routing, credential renewal, idle/wake and Slack delivery remain required for a persistent cloud harness. The temporary build-machine override was restored. PR9 and existing Slack routing are unchanged; no rollout flags or production routing were changed.