auth: move domain mode below app wire types (#29721)

## Why

Authentication mode is a domain concept used by login, model selection,
telemetry, and transports. Keeping the canonical type in app-server
protocol forces those lower-level crates to depend on an unrelated wire
API.

## What changed

- Added canonical `codex_protocol::auth::AuthMode` domain values.
- Kept the app-server wire DTO unchanged and added an explicit app-side
conversion.
- Removed production app-server-protocol dependencies from login,
model-provider-info, models-manager, and otel call paths.

## Stack

This is PR 2 of 6, stacked on [PR
#29714](https://github.com/openai/codex/pull/29714). Review only the
delta from `codex/split-json-rpc-protocols`. Next: [PR
#29722](https://github.com/openai/codex/pull/29722).

## Validation

- Auth and login coverage passed in the focused protocol/domain test
run.
- App-server account and auth conversion coverage passed.

codex-rs/core-plugins/src/manager_tests.rs

@@ -25,7 +25,6 @@ use crate::test_support::write_curated_plugin_sha_with as write_curated_plugin_s
 use crate::test_support::write_file;
 use crate::test_support::write_openai_api_curated_marketplace;
 use crate::test_support::write_openai_curated_marketplace;
-use codex_app_server_protocol::AuthMode;
 use codex_app_server_protocol::ConfigLayerSource;
 use codex_config::AppToolApproval;
 use codex_config::CONFIG_TOML_FILE;
@@ -44,6 +43,7 @@ use codex_core_skills::config_rules::SkillConfigRules;
 use codex_login::CodexAuth;
 use codex_plugin::AppDeclaration;
 use codex_plugin::PluginId;
+use codex_protocol::auth::AuthMode;
 use codex_protocol::protocol::HookEventName;
 use codex_protocol::protocol::Product;
 use codex_utils_absolute_path::AbsolutePathBuf;