Set up End-to-End Tests for CI with Dockerized Nodes

[snqre]

Objective

Run E2E tests that build and spin up bootstrap, client, server, and relay images in a CI environment to validate network functionality.

Background

Currently, E2E tests:

• Build Docker images from the target folder.
• Require a running Docker daemon.
• Are slow and resource-intensive.
• Are gated in Rust with feature flags.

Unit and integration tests run fast and are safe for PR validation.