docs(providers): drop stale disconnect comment; rewrite changelog bullet

Two nits from the openchamber-bot review at 65668f14:

- The disconnect handler carried a stale comment that referenced a
  "removed:false payload gating" feature the rebase removed; the
  helper below it does not do that gating. Drop the comment.
- The Hide button onClick ran setAuthPanelDismissedForId inside the
  setShowAuthPanel updater (idempotent today, impure under StrictMode
  double-invoke). Move both calls outside the updater.

Also rewrite the [Unreleased] changelog bullet to describe the
user-visible change (Connected + models visible for options.apiKey
providers) instead of internal mechanics ("source refetch + optimistic
auth mark"), and broaden the wording from "after saving" to cover
OAuth, custom-provider, and disconnect paths.

packages/ui/src/components/sections/providers/ProvidersPage.tsx

@@ -586,8 +586,6 @@ export const ProvidersPage: React.FC = () => {
       }
 
       toast.success(t('settings.providers.page.toast.providerDisconnected'));
-      // Only accumulate when the server actually deferred a restart (e.g. auth removed).
-      // removed:false payloads must not create a phantom pending Apply & Restart.
       // Use the helper so an externally managed OpenCode that requires a manual
       // restart records the deferred-restart guidance instead of toasting a
       // misleading "disconnect failed" for a write that already persisted.
@@ -940,15 +938,9 @@ export const ProvidersPage: React.FC = () => {
               size="xs"
               className="!font-normal"
               onClick={() => {
-                setShowAuthPanel((prev) => {
-                  const next = !prev;
-                  if (!next) {
-                    setAuthPanelDismissedForId(selectedProvider.id);
-                  } else {
-                    setAuthPanelDismissedForId(null);
-                  }
-                  return next;
-                });
+                const nextOpen = !showAuthPanel;
+                setShowAuthPanel(nextOpen);
+                setAuthPanelDismissedForId(nextOpen ? null : selectedProvider.id);
               }}
             >
               {showAuthPanel ? t('settings.providers.page.actions.hide') : t('settings.providers.page.actions.reconnect')}