[feat] Add remote config support for model upload and asset update feature flags (#7143)

## Summary
Feature flags for model upload button and asset update options now check
remote config from `/api/features` first, falling back to websocket
feature flags.

## Changes
- **What**: Added `model_upload_button_enabled` and
`asset_update_options_enabled` to `RemoteConfig` type
- **What**: Updated feature flag getters to prioritize remote config
over websocket flags
- **Why**: Enables dynamic feature control without requiring websocket
connection, consistent with other feature flags pattern

## Review Focus
- Pattern consistency with other remote config feature flags
- Proper fallback behavior when remote config is unavailable

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-7143-feat-Add-remote-config-support-for-model-upload-and-asset-update-feature-flags-2bf6d73d3650819cb364f0ab69d77dd0)
by [Unito](https://www.unito.io)

Co-authored-by: Claude <noreply@anthropic.com>

src/platform/remoteConfig/types.ts

@@ -34,4 +34,6 @@ export type RemoteConfig = {
   comfy_platform_base_url?: string
   firebase_config?: FirebaseRuntimeConfig
   telemetry_disabled_events?: TelemetryEventName[]
+  model_upload_button_enabled?: boolean
+  asset_update_options_enabled?: boolean
 }