fix(downloads): an upload's cancel, progress, failure and notice speak of an upload

- Cancelling an upload asks "Delete upload?" and says the uploaded file is
  removed from the server with it.
- The phone-safe conversion's real ffmpeg % shows as a bar ("Converting for
  phones"), not an indeterminate pulse.
- A failed upload is titled "The upload isn't ready", with its own reasons
  (convert_failed, retryable; upload_missing) instead of download copy.
- The inbox says "Upload ready to share" for a converted upload.

frontend/src/components/DownloadCenter.confirm.dom.test.tsx

@@ -124,4 +124,21 @@ describe("DownloadCenter confirm dialogs", () => {
       ["downloads.confirm.deleteTitle", "downloads.actions.delete"],
     ]);
   });
+
+  it("cancelling an upload says the uploaded file goes with it", async () => {
+    // Nothing to fetch again: the cancel deletes the original from the server.
+    mocks.jobs = [{ ...job(3, "queued"), job_kind: "upload" }];
+    render(
+      <QueryClientProvider client={new QueryClient()}>
+        <DownloadCenter />
+      </QueryClientProvider>,
+    );
+    await pick("Clip 3", "downloads.actions.cancel");
+    await waitFor(() => expect(mocks.confirm).toHaveBeenCalledTimes(1));
+    const [opts] = mocks.confirm.mock.calls[0]!;
+    expect([opts.title, opts.confirmLabel]).toEqual([
+      "downloads.confirm.cancelUploadTitle",
+      "downloads.confirm.cancelUploadAction",
+    ]);
+  });
 });