feat(cli): add sandbox profile config controls (#20118)

## Why

The explicit profile path from #20117 is meant for standalone testing,
but it still inherited the
shell cwd and all managed requirements implicitly. The pre-existing
launcher path even called out
that it did not support a separate cwd yet in

[`debug_sandbox.rs`](https://github.com/openai/codex/blob/509453f688a30929432be866402d1ea46aa12169/codex-rs/cli/src/debug_sandbox.rs#L174-L179).

For a standalone command, the useful default is to let the caller choose
the project directory being
tested and to avoid administrator-provided constraints unless the caller
explicitly wants to test
those too.

## What changed

- Add explicit-profile-only `-C/--cd DIR`, and use that cwd for both
profile resolution and command
  execution.
- Add explicit-profile-only `--include-managed-config`.
- Make explicit profile mode skip managed requirement sources by
default, including cloud
requirements, MDM requirements, `/etc/codex/requirements.toml`, and the
legacy managed-config
  requirements projection.
- Preserve all existing invocations outside the explicit-profile path.

## Stack

1. #20117 `sandbox-ui-profile`
2. #20118 `sandbox-ui-config` --> this PR

Both PRs are additive. Replay JSON is intentionally deferred to a
follow-up design pass.

## Tests ran

- `cargo test -p codex-cli debug_sandbox`
- `cargo test -p codex-cli sandbox_macos_`
- `cargo test -p codex-core
load_config_layers_can_ignore_managed_requirements`
- `cargo test -p codex-core
load_config_layers_includes_cloud_requirements`
- macOS branch-binary smoke on the rebased top of stack: `-C` changed
execution cwd, explicit
profile mode omitted managed proxy env under `env -i`, and
`--include-managed-config` restored it.
- Linux devbox branch-binary smoke on the rebased top of stack: `-C`
changed execution cwd for
  built-in and user-defined explicit profiles.

codex-rs/cli/src/main.rs

@@ -1946,6 +1946,14 @@ mod tests {
         assert_eq!(command.command, vec!["echo"]);
     }
 
+    #[test]
+    fn sandbox_macos_rejects_explicit_profile_controls_without_profile() {
+        let err = MultitoolCli::try_parse_from(["codex", "sandbox", "macos", "-C", "/tmp"])
+            .expect_err("parse should fail");
+
+        assert_eq!(err.kind(), clap::error::ErrorKind::MissingRequiredArgument);
+    }
+
     #[test]
     fn plugin_marketplace_remove_parses_under_plugin() {
         let cli =