desktop: Settings Models tab is missing the provider-level visibility toggle

Description

In Settings → Models, models are grouped by provider and each model has its own visibility switch. If a provider has a long list, I have to toggle them one by one.

There used to be a master switch on the provider row that turned all of that provider's models on or off. I still see that switch in the model picker's Manage models dialog, but it is missing from the Settings page.

The Settings tab was added in #29689 without this control. The manage dialog still has it (packages/app/src/providers/models/manage.tsx). I think Settings just never got the same header switch.

Plugins

Not relevant. This is a desktop Settings UI issue.

OpenCode version

0.0.0-beta-18269

Steps to reproduce

1. Open OpenCode Desktop.
2. Open Settings → Models.
3. Expand a provider with many models, e.g. DeepSeek.
4. Try to hide or show every model from that provider.

Expected: the provider row has a master switch, same as Manage models. Turning it off hides every model in that group from the model picker. Turning it on shows them all.

Actual: only per-model switches are available on the Settings page. I have to click each one.

Workaround: I can still use the master switch from the model picker → Manage models.

Suggested fix: reuse the existing providerVisible / setProviderVisibility logic from packages/app/src/providers/models/manage.tsx in packages/app/src/settings/models/models.tsx. Put the switch on the provider header and use the existing i18n key dialog.model.manage.provider.toggle. No backend or visibility-storage change should be needed.

Screenshot and/or share link

Operating System

macOS Darwin 25.6.0 arm64

Terminal

OpenCode Desktop (beta)