Add support for UDS in codex --remote (#22414)

## Why

Added support for UDS connections in `codex --remote`.

TUI also now connects to local app-server using UDS by default if it is
running and set to listen to UDS connection.

## What Changed

- Introduced `RemoteAppServerEndpoint` with `WebSocket` and `UnixSocket`
variants.
- Reused the existing JSON-RPC-over-WebSocket protocol over either a TCP
WebSocket stream or a UDS stream.
- Updated `codex --remote` to accept `ws://host:port`,
`wss://host:port`, `unix://`, and `unix://PATH`.
- Kept `--remote-auth-token-env` restricted to `wss://` and loopback
`ws://` remotes.
- Added a fast TUI startup probe for the default daemon socket, falling
back to the embedded app server when the daemon is absent or
unresponsive.

## Verification

- Manually verified that the updated remote flow works.
- Added coverage for UDS remote round trips, WebSocket auth headers,
auth-token transport policy, remote address parsing, and missing-daemon
fallback.
- Ran focused remote test coverage locally.

codex-rs/Cargo.lock

@@ -1970,6 +1970,8 @@ dependencies = [
  "codex-exec-server",
  "codex-feedback",
  "codex-protocol",
+ "codex-uds",
+ "codex-utils-absolute-path",
  "codex-utils-rustls-provider",
  "futures",
  "pretty_assertions",