docs: remove references to deleted OpenClaw REST facade (port 8004)

Update all documentation to reflect removal of OpenClaw REST service:
- README.md, README_zh.md: remove service table entry
- deploy/README.md: update port range 8000-8003
- services/README.md: remove 8004 references and service list
- docs/compat-removal-plan.md: remove REST surface mention
- docs/current-architecture.md: remove service reference
- docs/legacy-inventory.md: simplify to WebSocket-only description

Follow-up to: refactor(openclaw): remove REST facade

docs/current-architecture.md

@@ -83,7 +83,6 @@ Current service surfaces:
   - read-only explain/news APIs
 - `backend.apps.runtime_service` on `:8003`
   - runtime lifecycle and gateway process management
-- `backend.apps.openclaw_service` on `:8004`
   - optional OpenClaw REST facade
 - gateway WebSocket on `:8765`
   - live feed/event transport and pipeline coordination