fix(network-proxy): add unix socket allow-all and update seatbelt rules (#11368)

## Summary
Adds support for a Unix socket escape hatch so we can bypass socket
allowlisting when explicitly enabled.

## Description
* added a new flag, `network.dangerously_allow_all_unix_sockets` as an
explicit escape hatch
* In codex-network-proxy, enabling that flag now allows any absolute
Unix socket path from x-unix-socket instead of requiring each path to be
explicitly allowlisted. Relative paths are still rejected.
* updated the macOS seatbelt path in core so it enforces the same Unix
socket behavior:
  * allowlisted sockets generate explicit network* subpath rules
  * allow-all generates a broad network* (subpath "/") rule

---------

Co-authored-by: Codex <199175422+chatgpt-codex-connector[bot]@users.noreply.github.com>

codex-rs/app-server-protocol/src/protocol/v2.rs

@@ -577,6 +577,7 @@ pub struct NetworkRequirements {
     pub allow_upstream_proxy: Option<bool>,
     pub dangerously_allow_non_loopback_proxy: Option<bool>,
     pub dangerously_allow_non_loopback_admin: Option<bool>,
+    pub dangerously_allow_all_unix_sockets: Option<bool>,
     pub allowed_domains: Option<Vec<String>>,
     pub denied_domains: Option<Vec<String>>,
     pub allow_unix_sockets: Option<Vec<String>>,