core: remove stale apply_patch SandboxPolicy TODO in seatbelt (#11345)

The `TODO` in `core/src/seatbelt.rs` claimed that `apply_patch` still needed to honor `SandboxPolicy`. That was true when the comment was added, but it is no longer true.

Analysis:
- The TODO was introduced in #1762, when seatbelt code was split out of `exec.rs`.
- `apply_patch` sandboxing was later implemented in #1705.
- Today, `apply_patch` calls are routed through the tool orchestrator and delegated to `ApplyPatchRuntime`, which executes via `execute_env()` using the active sandbox attempt policy.
- On macOS, the sandbox transform path for that execution still builds seatbelt args with `create_seatbelt_command_args(command, policy, sandbox_policy_cwd)`, so the same `SandboxPolicy` gates `apply_patch` writes and network behavior.

Because this behavior is already enforced, the TODO is stale and removing it avoids implying missing sandbox coverage where none exists.

No functional behavior change; comment-only cleanup.

codex-rs/core/src/seatbelt.rs

@@ -243,7 +243,6 @@ pub(crate) fn create_seatbelt_command_args(
         ""
     };
 
-    // TODO(mbolin): apply_patch calls must also honor the SandboxPolicy.
     let proxy = proxy_policy_inputs(network);
     let network_policy = dynamic_network_policy(sandbox_policy, enforce_managed_network, &proxy);