Codex catalog sync ignores on-disk changes to catalog override/customizations and strips template speed tiers

Summary

Background Codex catalog synchronization overwrites external updates to codex_models/model-catalog.json and codex_models/model-customizations.json:
load_codex_model_catalog_override and load_codex_model_customizations are called only once during application startup (main.rs). Meanwhile, start_codex_model_catalog_sync runs refresh_applied_codex_model_catalog every 30 seconds and regenerates ~/.codex/cpa-gui-model-catalog.json from the in-memory CatalogState loaded at launch. If either codex_models/model-catalog.json or codex_models/model-customizations.json is updated or removed on disk while the app is running, the 30-second background sync ignores the on-disk change and overwrites ~/.codex/cpa-gui-model-catalog.json with the stale in-memory state.
enable_fast_mode discards additional speed tiers from catalog templates:
In src-tauri/src/codex_catalog.rs, enable_fast_mode unconditionally replaces service_tiers with [{"id": "priority", "name": "Fast", "description": "1.5x speed, increased usage"}] and additional_speed_tiers with ["fast"]. When a catalog template or local catalog override defines additional speed tiers (such as ultrafast) or custom priority descriptions, they are stripped from the generated ~/.codex/cpa-gui-model-catalog.json.

Launch EasyCLIProxyAPI with Codex configured.
Edit <app_data>/codex_models/model-customizations.json or <app_data>/codex_models/model-catalog.json on disk (for example, changing effective_context_window_percent or adding an additional entry in service_tiers / additional_speed_tiers).
Wait up to 30 seconds for start_codex_model_catalog_sync to run.
Inspect ~/.codex/cpa-gui-model-catalog.json: the generated file reverts to the startup in-memory snapshot, and any non-priority entries in service_tiers / additional_speed_tiers are stripped.

Before regenerating the Codex catalog or opening/saving the catalog editor, EasyCLIProxyAPI reloads codex_models/model-catalog.json and codex_models/model-customizations.json if their on-disk size or modification time changed (and resets to the embedded catalog / empty customizations if the file was removed), while keeping the previously loaded state if a modified file fails validation.
enable_fast_mode ensures priority (Fast) and "fast" are present while preserving valid additional service_tiers and additional_speed_tiers entries from the template.