fix(desktop): show the launch-source preference for a single connection

The toggle was gated on having 2+ registered sources, which hid it in exactly
the local-only state the drift produces — the state where a user most needs to
change what launch restores.

apps/desktop/src/app/settings/connections-registry.test.tsx

@@ -161,13 +161,16 @@ describe('ConnectionsRegistrySection', () => {
     await waitFor(() => expect(setLaunchMode).toHaveBeenCalledWith('last-used'))
   })
 
-  it('keeps the launch preference out of the way for a single source', async () => {
+  it('offers the launch preference even for a single source', async () => {
+    // A local-only registry is the drift state from #90174, and the launch
+    // toggle is the control that lets a user out of it. Hiding it there left
+    // hand-editing connections.json as the only recourse.
     list.mockResolvedValueOnce({ ...registry, connections: [registry.connections[0]] })
 
     render(<ConnectionsRegistrySection />)
 
     await waitFor(() => expect(list).toHaveBeenCalledTimes(1))
-    expect(screen.queryByText('At startup, return to Sessions on the last-used gateway')).toBeNull()
+    expect(screen.getByText('At startup, return to Sessions on the last-used gateway')).toBeTruthy()
   })
 
   it('keeps search out of the way for a small registry', async () => {

apps/desktop/src/app/settings/connections-registry.tsx

@@ -989,7 +989,11 @@ export function ConnectionsRegistrySection() {
         </div>
       )}
 
-      {!loading && registry && registry.connections.length > 1 && (
+      {/* Not gated on connections.length > 1: a registry that drifted down to
+          local-only is exactly the state where a user needs to see and change
+          the launch behavior, and hiding the control there left hand-editing
+          connections.json as the only recourse (#90174). */}
+      {!loading && registry && (
         <div className="mt-6 border-t border-border/60 pt-4">
           <ToggleRow
             checked={registry.launchMode === 'last-used'}