fix(desktop): remount provider config panel when the provider changes

The panel instance survived a provider switch, so an in-flight fetch for the
old provider could resolve last and seed the new provider's panel with the
wrong schema — Save would then PUT those keys to the new provider's endpoint.
Key the mount on the provider name.

apps/desktop/src/app/settings/config-settings.tsx

@@ -411,7 +411,7 @@ export function ConfigSettings({
                 value={getNested(config, key)}
               />
               {key === 'memory.provider' && typeof getNested(config, key) === 'string' && getNested(config, key) ? (
-                <ProviderConfigPanel provider={String(getNested(config, key))} />
+                <ProviderConfigPanel key={String(getNested(config, key))} provider={String(getNested(config, key))} />
               ) : null}
             </div>
           ))}