feat: codex-linux-sandbox standalone executable (#740)

This introduces a standalone executable that run the equivalent of the
`codex debug landlock` subcommand and updates `rust-release.yml` to
include it in the release.

The idea is that we will include this small binary with the TypeScript
CLI to provide support for Linux sandboxing.

codex-rs/cli/src/lib.rs

@@ -0,0 +1,47 @@
+#[cfg(target_os = "linux")]
+pub mod landlock;
+pub mod proto;
+pub mod seatbelt;
+
+use clap::Parser;
+use codex_core::protocol::SandboxPolicy;
+use codex_core::SandboxPermissionOption;
+
+#[derive(Debug, Parser)]
+pub struct SeatbeltCommand {
+    /// Convenience alias for low-friction sandboxed automatic execution (network-disabled sandbox that can write to cwd and TMPDIR)
+    #[arg(long = "full-auto", default_value_t = false)]
+    pub full_auto: bool,
+
+    #[clap(flatten)]
+    pub sandbox: SandboxPermissionOption,
+
+    /// Full command args to run under seatbelt.
+    #[arg(trailing_var_arg = true)]
+    pub command: Vec<String>,
+}
+
+#[derive(Debug, Parser)]
+pub struct LandlockCommand {
+    /// Convenience alias for low-friction sandboxed automatic execution (network-disabled sandbox that can write to cwd and TMPDIR)
+    #[arg(long = "full-auto", default_value_t = false)]
+    pub full_auto: bool,
+
+    #[clap(flatten)]
+    pub sandbox: SandboxPermissionOption,
+
+    /// Full command args to run under landlock.
+    #[arg(trailing_var_arg = true)]
+    pub command: Vec<String>,
+}
+
+pub fn create_sandbox_policy(full_auto: bool, sandbox: SandboxPermissionOption) -> SandboxPolicy {
+    if full_auto {
+        SandboxPolicy::new_full_auto_policy()
+    } else {
+        match sandbox.permissions.map(Into::into) {
+            Some(sandbox_policy) => sandbox_policy,
+            None => SandboxPolicy::new_read_only_policy(),
+        }
+    }
+}