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/login/tests/suite/auth_refresh.rs

@@ -3,7 +3,6 @@ use anyhow::Result;
 use base64::Engine;
 use chrono::Duration;
 use chrono::Utc;
-use codex_app_server_protocol::AuthMode;
 use codex_config::types::AuthCredentialsStoreMode;
 use codex_login::AuthDotJson;
 use codex_login::AuthKeyringBackendKind;
@@ -15,6 +14,7 @@ use codex_login::load_auth_dot_json;
 use codex_login::save_auth;
 use codex_login::token_data::IdTokenInfo;
 use codex_login::token_data::TokenData;
+use codex_protocol::auth::AuthMode;
 use codex_protocol::auth::RefreshTokenFailedReason;
 use core_test_support::skip_if_no_network;
 use pretty_assertions::assert_eq;

codex-rs/login/tests/suite/logout.rs

@@ -1,7 +1,6 @@
 use anyhow::Context;
 use anyhow::Result;
 use base64::Engine;
-use codex_app_server_protocol::AuthMode;
 use codex_config::types::AuthCredentialsStoreMode;
 use codex_login::AuthDotJson;
 use codex_login::AuthKeyringBackendKind;
@@ -14,6 +13,7 @@ use codex_login::logout_with_revoke;
 use codex_login::save_auth;
 use codex_login::token_data::IdTokenInfo;
 use codex_login::token_data::TokenData;
+use codex_protocol::auth::AuthMode;
 use core_test_support::skip_if_no_network;
 use pretty_assertions::assert_eq;
 use serde_json::Value;