image-gen-core (#13290)

Core tool-calling for image-gen, handles requesting and receiving logic
for images using response API

codex-rs/otel/src/traces/otel_manager.rs

@@ -771,6 +771,7 @@ impl OtelManager {
             ResponseItem::CustomToolCall { .. } => "custom_tool_call".into(),
             ResponseItem::CustomToolCallOutput { .. } => "custom_tool_call_output".into(),
             ResponseItem::WebSearchCall { .. } => "web_search_call".into(),
+            ResponseItem::ImageGenerationCall { .. } => "image_generation_call".into(),
             ResponseItem::GhostSnapshot { .. } => "ghost_snapshot".into(),
             ResponseItem::Compaction { .. } => "compaction".into(),
             ResponseItem::Other => "other".into(),