🐛Bugfix: Model config race conditions during connectivity verification and provider save

[ayiya12]

Summary

Fix two race conditions in the model configuration flow:

1. Stale connectivity responses — Users could modify form fields while connectivity verification was in flight, causing returned responses to be applied to outdated state. Fix: lock all form inputs via disabled={verifyingConnectivity}, propagating the lock to ModelCapacityFields and ModelMaxTokensInput through a new disabled prop.

2. Stale API key after provider save — After saving a new provider API key, the model list was prefetched with the previous key because the parent's models state had not yet propagated into the closure. Fix: add an onSuccess callback to ProviderConfigEditDialog that passes the just-saved apiKey directly into prefetchProviderModels via a new apiKeyOverride, and force a full remount via key so the dialog always initializes from the latest initialApiKey.

Changes

• frontend/app/[locale]/models/components/model/ModelAddDialog.tsx — disable all form fields during verification and reflect the verifying state on the Add button
• frontend/app/[locale]/models/components/model/ModelCapacityFields.tsx — add disabled prop and forward to children
• frontend/app/[locale]/models/components/model/ModelMaxTokensInput.tsx — add disabled prop and forward to children
• frontend/app/[locale]/models/components/model/ModelEditDialog.tsx — add onSuccess callback to ProviderConfigEditDialog
• frontend/app/[locale]/models/components/model/ModelDeleteDialog.tsx — add apiKeyOverride to prefetchProviderModels, invoke it in onSuccess with the saved key, and force remount via key prop