unifying all image saves to /tmp to bug-proof (#14149)

image-gen feature will have the model saving to /tmp by default + at all
times

codex-rs/core/src/context_manager/history_tests.rs

@@ -434,9 +434,6 @@ fn for_prompt_rewrites_image_generation_calls_when_images_are_supported() {
                     ContentItem::InputImage {
                         image_url: "data:image/png;base64,Zm9v".to_string(),
                     },
-                    ContentItem::InputText {
-                        text: "Saved to: CWD".to_string(),
-                    },
                 ],
                 end_turn: None,
                 phase: None,
@@ -503,9 +500,6 @@ fn for_prompt_rewrites_image_generation_calls_when_images_are_unsupported() {
                         text: "image content omitted because you do not support image input"
                             .to_string(),
                     },
-                    ContentItem::InputText {
-                        text: "Saved to: CWD".to_string(),
-                    },
                 ],
                 end_turn: None,
                 phase: None,

codex-rs/core/src/context_manager/normalize.rs

@@ -242,9 +242,6 @@ pub(crate) fn rewrite_image_generation_calls_for_stateless_input(items: &mut Vec
                             text: format!("Prompt: {revised_prompt}"),
                         },
                         ContentItem::InputImage { image_url },
-                        ContentItem::InputText {
-                            text: "Saved to: CWD".to_string(),
-                        },
                     ],
                     end_turn: None,
                     phase: None,