test(zenoh): Add integration tests with actual Zenoh router

[zhexuany]

Testing Task

Add integration tests that communicate with an actual Zenoh router.

Motivation

Current unit tests mock or skip Zenoh functionality. Integration tests verify actual pub/sub communication, connection lifecycle, message serialization, and router failover.

Proposed Solution

1. Create Docker Compose setup with Zenoh router
2. Add integration tests that connect to the router
3. Test publish/subscribe end-to-end

Files to Add

• middlewares/zenoh/docker-compose.test.yml
• middlewares/zenoh/src/zenoh_plugin/test/integration/

Priority

Medium - Unit tests catch most bugs