Non-interactive mode doesn't properly close HTTP connections on exit

What version of Codex CLI is running?

0.118.0

What subscription do you have?

Free

Which model were you using?

_No response_

What platform is your computer?

_No response_

What terminal emulator and version are you using (if applicable)?

_No response_

What issue are you seeing?

Codex CLI in non-interactive mode calls std::process::exit() throughout error paths, terminating the process without properly closing HTTP connections. This causes session leaks on proxy servers that track concurrent connections.

What steps can reproduce the bug?

1. Run a simple non-interactive command

codex "echo hello"

2. Check proxy server active sessions immediately

Expected: Session count decreases

Actual: Session count remains elevated (5 min TTL)

What is the expected behavior?

_No response_

Additional information

Found 13 instances of std::process::exit(1) in codex-rs/exec/src/lib.rs:

// Line 524: Git check fails
if get_git_repo_root(&default_cwd).is_none() {
    std::process::exit(1); // ❌ No cleanup
}

// Line 828: Error exit
if error_seen {
    std::process::exit(1); // ❌ Bypasses Drop
}

// ... 11 more instances

Problem: exit() bypasses Drop traits → HTTP connections close abruptly → server can't detect session end → session count leaks until TTL expires.