[Epic] Embed Rust services into Java microservice architecture via cloud integration

[philipgreat]

Summary

Embed Rust services built with teaql-rs into a Java-dominated microservice architecture by providing cloud-native capabilities:

• Service discovery & registration (Nacos v2 gRPC)
• Configuration center integration
• Health check & operational endpoints (Spring Boot Actuator compatible)
• Prometheus metrics (pull + push gateway)
• Graceful shutdown

Design Document

docs/2026-07-20-cloud-integration-design.md

Branch

feature/cloud-integration

New Crates

• teaql-cloud-core — Core traits & shared models
• teaql-cloud-actuator — Axum operational endpoints
• teaql-cloud-nacos — Nacos v2 gRPC implementation (nacos-sdk =0.8)
• teaql-cloud-starter — One-line bootstrap convenience API
• Integration tests
• CI updates
• Documentation updates