fix(settings): correct Gemini default visibility to true (#818)

Frontend fallback value for visibleApps had gemini: false, which was
inconsistent with backend default (gemini: true). This caused Gemini
to be hidden by default on first install.

Fixes #817

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

src/components/settings/AppVisibilitySettings.tsx

@@ -31,7 +31,7 @@ export function AppVisibilitySettings({
   const visibleApps: VisibleApps = settings.visibleApps ?? {
     claude: true,
     codex: true,
-    gemini: false,
+    gemini: true,
     opencode: true,
   };