fix(review): resolve deep-review findings across quickfix batch #2

- Button: `loading` always disables (|| not ??) — stops a double-submit
  when a call-site passes an explicit boolean `disabled` (VideoEditor).
- playlists: track un-ingestable-but-live YouTube ids in the sync baseline
  so a linked playlist containing a private/deleted video converges instead
  of re-classifying it as a pending pull forever; re-attempt ingestion each
  sync so a restored (private->public) video heals, and prune ids that
  leave YouTube.
- SettingsPanel: download-auth section renders an honest error/loading
  state (StateMessage + retry) instead of a bare empty section on a failed
  credentials fetch; HU+EN loadError string.
- tests: reorder-order, partial-failure baseline hold, un-ingestable
  converge/heal/prune, Button loading-disables, download-auth error/retry.

frontend/src/components/SettingsPanel.downloadAuth.dom.test.tsx

@@ -33,7 +33,12 @@ import { DownloadAuth } from "./SettingsPanel";
 
 const HOSTS = [
   { host_key: "facebook", label: "Facebook", configured: false, updated_at: null },
-  { host_key: "instagram", label: "Instagram", configured: true, updated_at: "2026-08-01T00:00:00Z" },
+  {
+    host_key: "instagram",
+    label: "Instagram",
+    configured: true,
+    updated_at: "2026-08-01T00:00:00Z",
+  },
 ];
 
 function renderPanel() {
@@ -73,7 +78,9 @@ describe("DownloadAuth (write-only cookies)", () => {
     const field = (await screen.findByTestId("cookie-input-facebook")) as HTMLTextAreaElement;
     expect(field.value).toBe(""); // write-only: never prefilled
 
-    fireEvent.change(field, { target: { value: "# Netscape\n.facebook.com\tTRUE\t/\tT\t0\tc\t1\n" } });
+    fireEvent.change(field, {
+      target: { value: "# Netscape\n.facebook.com\tTRUE\t/\tT\t0\tc\t1\n" },
+    });
     fireEvent.click(screen.getByText("settings.downloadAuth.save"));
     await waitFor(() =>
       expect(h.setDownloadCredential).toHaveBeenCalledWith(
@@ -90,4 +97,17 @@ describe("DownloadAuth (write-only cookies)", () => {
     const field = (await screen.findByTestId("cookie-input-instagram")) as HTMLTextAreaElement;
     expect(field.value).toBe(""); // the stored blob is never fetched into the field
   });
+
+  it("renders an honest error state with retry when the fetch fails, not an empty section", async () => {
+    // Honest-states: a failed load must NOT render as a bare empty section (no host rows).
+    h.downloadCredentials.mockRejectedValueOnce(new Error("boom"));
+    h.downloadCredentials.mockResolvedValue({ hosts: HOSTS });
+    renderPanel();
+    // The error message shows and no host rows render.
+    await screen.findByText("settings.downloadAuth.loadError");
+    expect(screen.queryByTestId("cookie-host-facebook")).toBeNull();
+    // Retry refetches → the list appears.
+    fireEvent.click(screen.getByText("common.retry"));
+    await screen.findByTestId("cookie-host-facebook");
+  });
 });