feat: add use memories config (#12997)

codex-rs/core/src/config/mod.rs

@@ -2490,6 +2490,7 @@ persistence = "none"
 
         let memories = r#"
 [memories]
+use_memories = false
 max_raw_memories_for_global = 512
 max_unused_days = 21
 max_rollout_age_days = 42
@@ -2502,6 +2503,7 @@ phase_2_model = "gpt-5"
             toml::from_str::<ConfigToml>(memories).expect("TOML deserialization should succeed");
         assert_eq!(
             Some(MemoriesToml {
+                use_memories: Some(false),
                 max_raw_memories_for_global: Some(512),
                 max_unused_days: Some(21),
                 max_rollout_age_days: Some(42),
@@ -2522,6 +2524,7 @@ phase_2_model = "gpt-5"
         assert_eq!(
             config.memories,
             MemoriesConfig {
+                use_memories: false,
                 max_raw_memories_for_global: 512,
                 max_unused_days: 21,
                 max_rollout_age_days: 42,