## What changed
- Move the reusable WebSocket relay, registration, frame capture, and encryption assertion helpers into `codex-exec-server-test-support`.
- Re-export the helpers from the existing relay test module so its callers keep the same interface.
- Add the Cargo dependencies and Bazel proto compile data required by the shared support module.
GitOrigin-RevId: 0383149c79ef86cb5e64a09baec41332f9eec4c6
## Why
The TUI must inspect the default execution environment before loading its final
configuration. Initializing the environment manager at that point can give
startup services the bootstrap HTTP policy instead of the effective policy after
managed requirements are applied.
## What changed
- Split environment discovery from manager construction so callers can inspect
the default environment without starting remote connections.
- Build the environment manager after final configuration loading and pass its
resolved `HttpClientFactory` through all construction paths.
- Add shared test support for managers that use the legacy default HTTP policy.
## Testing
- Cover connection-free environment discovery and explicit HTTP policy
propagation.
- Verify TUI startup services use the final managed `respect_system_proxy` value.
GitOrigin-RevId: 928fa31e6b4bcfbe1a121cade2f351427fdfa0f4
