Record attempted tool calls in response metadata (#36181)

## What changed

- Add the opt-in `executed_tool_call_metadata` feature to record model-attempted direct and code-mode tool calls.
- Attach recorded names and arguments to the matching tool output in the next Responses request, preserving the metadata across sampling retries.
- Bound pending calls and argument sizes, and emit truncation metadata when limits are exceeded.

## Testing

- Cover disabled-by-default behavior, namespaced and nested calls, blocked or failed attempts, retry handling, and recorder limits.

GitOrigin-RevId: 5ce917b73e797b0f6904d46477b9d2cf8ea71bf2

codex-rs/features/src/lib.rs

@@ -92,6 +92,8 @@ pub enum Feature {
     SecretAuthStorage,
 
     // Experimental
+    /// Record model-attempted tool calls in internal Responses metadata.
+    ExecutedToolCallMetadata,
     /// Enable JavaScript code mode backed by the in-process V8 runtime.
     CodeMode,
     /// Use a 30-second default yield timeout for code mode exec calls.
@@ -889,6 +891,12 @@ pub const FEATURES: &[FeatureSpec] = &[
         stage: Stage::Removed,
         default_enabled: false,
     },
+    FeatureSpec {
+        id: Feature::ExecutedToolCallMetadata,
+        key: "executed_tool_call_metadata",
+        stage: Stage::UnderDevelopment,
+        default_enabled: false,
+    },
     FeatureSpec {
         id: Feature::CodeMode,
         key: "code_mode",