fix: Enable native Fast service tier UI for API-key auth

[moooyy]

Problem

API-key sessions can send a Fast/priority service tier through Codex++ request wrapping, but Codex's native service-tier UI remains gated behind ChatGPT
account auth. That means API-key users do not get the same speed selector and speed indicator that account-login users see.

A renderer/CDP-only patch is also too late for this path: Codex can load use-service-tier-settings-* and read-service-tier-for-request-* before Codex+

• injects into the webview. In that case the native UI logic is already initialized with the original ChatGPT-only gate.

Approach

Move the native service-tier renderer-module patch to Codex startup, before Codex registers and serves its app:// web assets.

Codex++ now prepares a small main-process preload and starts the macOS Codex bundle executable with NODE_OPTIONS=--require=<preload>. The preload hooks
Node's module loader, waits for Electron to be required, then wraps electron.protocol.handle before Codex registers the app:// handler.

Solution

• Generate service-tier-preload.js under the Codex++ state directory.
• Patch only the two native service-tier assets served through app://:
  • use-service-tier-settings-*.js
  • read-service-tier-for-request-*.js
• Allow apikey auth to use the same native service-tier settings path as chatgpt auth.
• Keep explicit service_tier validation tied to the selected model instead of bypassing model/service-tier support checks.
• Launch macOS Codex via the bundle executable instead of open -a, so the preload environment is applied before Electron loads the app modules.
• Keep Codex++ request wrapping aligned by sending both serviceTier and service_tier when a request-tier override is applied.
• Enable Codex++ service-tier controls by default so API-key users can see and use the speed selector/indicator path without an extra hidden setting.

Testing

• cargo fmt --check
• cargo test -p codex-plus-core service_tier_preload
• cargo test -p codex-plus-core --test cdp_bridge
• cargo test -p codex-plus-core --test launcher
• cd apps/codex-plus-manager && npm ci && npm run vite:build
• cargo clippy --all-features (passes; existing upstream warnings are still emitted)
• cargo test --all-features (all tests pass except the existing upstream baseline failure codex-plus-manager --test windows_subsystem relay_settings_keeps_profile_config_and_auth_files_isolated, which also fails on clean main because App.tsx does not contain
  snapshotActiveRelayFilesBeforeSwitch)
• Manual macOS launch verification from the local build: diagnostic logs showed launcher.service_tier_preload_enabled, service_tier_preload_loaded,
  service_tier_preload_protocol_patch_installed, and service_tier_preload_asset_patched for both service-tier renderer assets before the renderer
  injection path was needed.