extract models manager and related ownership from core (#16508)

## Summary
- split `models-manager` out of `core` and add `ModelsManagerConfig`
plus `Config::to_models_manager_config()` so model metadata paths stop
depending on `core::Config`
- move login-owned/auth-owned code out of `core` into `codex-login`,
move model provider config into `codex-model-provider-info`, move API
bridge mapping into `codex-api`, move protocol-owned types/impls into
`codex-protocol`, and move response debug helpers into a dedicated
`response-debug-context` crate
- move feedback tag emission into `codex-feedback`, relocate tests to
the crates that now own the code, and keep broad temporary re-exports so
this PR avoids a giant import-only rewrite

## Major moves and decisions
- created `codex-models-manager` as the owner for model
cache/catalog/config/model info logic, including the new
`ModelsManagerConfig` struct
- created `codex-model-provider-info` as the owner for provider config
parsing/defaults and kept temporary `codex-login`/`codex-core`
re-exports for old import paths
- moved `api_bridge` error mapping + `CoreAuthProvider` into
`codex-api`, while `codex-login::api_bridge` temporarily re-exports
those symbols and keeps the `auth_provider_from_auth` wrapper
- moved `auth_env_telemetry` and `provider_auth` ownership to
`codex-login`
- moved `CodexErr` ownership to `codex-protocol::error`, plus
`StreamOutput`, `bytes_to_string_smart`, and network policy helpers to
protocol-owned modules
- created `codex-response-debug-context` for
`extract_response_debug_context`, `telemetry_transport_error_message`,
and related response-debug plumbing instead of leaving that behavior in
`core`
- moved `FeedbackRequestTags`, `emit_feedback_request_tags`, and
`emit_feedback_request_tags_with_auth_env` to `codex-feedback`
- deferred removal of temporary re-exports and the mechanical import
rewrites to a stacked follow-up PR so this PR stays reviewable

## Test moves
- moved auth refresh coverage from `core/tests/suite/auth_refresh.rs` to
`login/tests/suite/auth_refresh.rs`
- moved text encoding coverage from
`core/tests/suite/text_encoding_fix.rs` to
`protocol/src/exec_output_tests.rs`
- moved model info override coverage from
`core/tests/suite/model_info_overrides.rs` to
`models-manager/src/model_info_overrides_tests.rs`

---------

Co-authored-by: Codex <noreply@openai.com>

codex-rs/core/tests/suite/remote_models.rs

@@ -105,7 +105,9 @@ async fn remote_models_get_model_info_uses_longest_matching_prefix() -> Result<(
 
     manager.list_models(RefreshStrategy::OnlineIfUncached).await;
 
-    let model_info = manager.get_model_info("gpt-5.3-codex-test", &config).await;
+    let model_info = manager
+        .get_model_info("gpt-5.3-codex-test", &config.to_models_manager_config())
+        .await;
 
     assert_eq!(model_info.slug, "gpt-5.3-codex-test");
     assert_eq!(model_info.base_instructions, specific.base_instructions);
@@ -348,7 +350,7 @@ async fn remote_models_remote_model_uses_unified_exec() -> Result<()> {
     assert_eq!(requests[0].url.path(), "/v1/models");
 
     let model_info = models_manager
-        .get_model_info(REMOTE_MODEL_SLUG, &config)
+        .get_model_info(REMOTE_MODEL_SLUG, &config.to_models_manager_config())
         .await;
     assert_eq!(model_info.shell_type, ConfigShellToolType::UnifiedExec);
 
@@ -455,7 +457,9 @@ async fn remote_models_truncation_policy_without_override_preserves_remote() ->
     let models_manager = test.thread_manager.get_models_manager();
     wait_for_model_available(&models_manager, slug).await;
 
-    let model_info = models_manager.get_model_info(slug, &test.config).await;
+    let model_info = models_manager
+        .get_model_info(slug, &test.config.to_models_manager_config())
+        .await;
     assert_eq!(
         model_info.truncation_policy,
         TruncationPolicyConfig::bytes(/*limit*/ 12_000)
@@ -500,7 +504,9 @@ async fn remote_models_truncation_policy_with_tool_output_override() -> Result<(
     let models_manager = test.thread_manager.get_models_manager();
     wait_for_model_available(&models_manager, slug).await;
 
-    let model_info = models_manager.get_model_info(slug, &test.config).await;
+    let model_info = models_manager
+        .get_model_info(slug, &test.config.to_models_manager_config())
+        .await;
     assert_eq!(
         model_info.truncation_policy,
         TruncationPolicyConfig::bytes(/*limit*/ 200)
@@ -628,7 +634,9 @@ async fn remote_models_apply_remote_base_instructions() -> Result<()> {
 
     wait_for_event(&codex, |event| matches!(event, EventMsg::TurnComplete(_))).await;
 
-    let base_model_info = models_manager.get_model_info("gpt-5.1", &config).await;
+    let base_model_info = models_manager
+        .get_model_info("gpt-5.1", &config.to_models_manager_config())
+        .await;
     let body = response_mock.single_request().body_json();
     let instructions = body["instructions"].as_str().unwrap();
     assert_eq!(instructions, base_model_info.base_instructions);
@@ -968,8 +976,8 @@ async fn wait_for_model_available(manager: &Arc<ModelsManager>, slug: &str) -> M
 }
 
 fn bundled_model_slug() -> String {
-    let response: ModelsResponse = serde_json::from_str(include_str!("../../models.json"))
-        .expect("bundled models.json should deserialize");
+    let response = codex_models_manager::bundled_models_response()
+        .unwrap_or_else(|err| panic!("bundled models.json should parse: {err}"));
     response
         .models
         .first()