feat(FN-3068): wire plugin slot mounts and enhance planning mode modal UI

This merge incorporates UI enhancements for the planning mode modal and quick chat FAB, moves the drag handle into provider actions, wires required plugin slot mounts, and adds tests for MobileNavBar and UsageIndicator components. The changes span the dashboard UI components with styling and behavio

Fusion-Task-Id: FN-3068

packages/dashboard/app/components/SettingsModal.tsx

@@ -4978,6 +4978,8 @@ export function SettingsModal({
               </div>
             ) : (
               <div className="auth-panel-body">
+              <PluginSlot slotId="settings-provider-card" projectId={projectId} />
+              <PluginSlot slotId="settings-integration-card" projectId={projectId} />
               {!showAuthenticatedGroup && (
                 <div className="auth-section-hint">
                   Sign in to at least one provider to get started with AI models.