fix: gate model default features on global config and user permissions
If you disabled code interpreter globally and in user permissions but
enabled it as a default feature on a model, the code interpreter pill
still appeared in the chat input. Same issue for web search and image
generation.
The setDefaults function in Chat.svelte activated model default features
based solely on the model's capability flag, ignoring whether the feature
was globally enabled or allowed by user permissions. Added the same
global config and user permission checks already used by the integrations
menu visibility and the features object sent to the backend.