Migrate GPT-5.4 uses to GPT-5.6 variants (#33173)

## What changed

- Hide `gpt-5.4` and `gpt-5.4-mini` from model selection and direct existing users to `gpt-5.6-terra` and `gpt-5.6-luna`, respectively.
- Use Terra for memory consolidation and Luna for memory extraction and rate-limit switch prompts.
- Keep Amazon Bedrock GPT-5 catalog entries visible when their bundled model metadata is hidden.

## Testing

- Add coverage that all Amazon Bedrock GPT-5 models remain visible and update TUI expectations for the new model choices.

GitOrigin-RevId: fd69c8d5fb6b510c77204df6b7ac3f07e67cded2

codex-rs/model-provider/src/amazon_bedrock/catalog.rs

@@ -5,6 +5,7 @@ use codex_model_provider_info::AMAZON_BEDROCK_GPT_5_6_SOL_MODEL_ID;
 use codex_model_provider_info::AMAZON_BEDROCK_GPT_5_6_TERRA_MODEL_ID;
 use codex_models_manager::bundled_models_response;
 use codex_protocol::openai_models::ModelInfo;
+use codex_protocol::openai_models::ModelVisibility;
 use codex_protocol::openai_models::ModelsResponse;
 use codex_protocol::openai_models::ReasoningEffort;
 use codex_protocol::openai_models::ReasoningEffortPreset;
@@ -75,6 +76,7 @@ fn gpt_5_bedrock_model(
     model.priority = priority;
     model.context_window = Some(GPT_5_BEDROCK_CONTEXT_WINDOW);
     model.max_context_window = Some(GPT_5_BEDROCK_CONTEXT_WINDOW);
+    model.visibility = ModelVisibility::List;
     model.availability_nux = None;
     model.upgrade = None;
     model
@@ -164,6 +166,15 @@ mod tests {
         }
     }
 
+    #[test]
+    fn gpt_5_bedrock_models_are_visible() {
+        let catalog = static_model_catalog();
+
+        for model in catalog.models {
+            assert_eq!(model.visibility, ModelVisibility::List);
+        }
+    }
+
     #[test]
     fn gpt_5_6_bedrock_models_use_variant_metadata_and_max_reasoning_effort() {
         let catalog = static_model_catalog();