feat(stream): friendlier pagination loading + error retry

- Replace the bare '…' loading dots at the bottom of the post stream
  with a skeleton bubble that matches the initial-load placeholders, so
  pagination feels like content arriving instead of a frozen indicator.
- Localize the retry control via new 'retry' / 'loadMoreFailed' keys
  across all 7 locales and surface a user-friendly error string instead
  of the raw exception message.
- Retry button now picks reset() vs loadMore() based on item count so a
  pagination failure only refetches the next page, not the whole stream.
- When a banner deep-link can't find its target post and pagination
  errors, break out of the retry loop and release the scroll lock so the
  user sees the inline retry instead of an endless freeze.

Verified in the browser: zh-CN renders '加载更多资料失败，请检查网络后重试。'
with a '重试' button; banner clicks with empty / '#' / 'javascript:' /
null linkUrls render no anchor and do not navigate.

src/locales/vi.ts

@@ -126,6 +126,8 @@ export const viDict: Dict = {
   tagsCommaLabel: "Thẻ (cách nhau bằng dấu phẩy)",
   uploadFile: "Tải lên",
   loading: "Đang tải…",
+  loadMoreFailed: "Không thể tải thêm bài. Hãy kiểm tra kết nối và thử lại.",
+  retry: "Thử lại",
   paginationPrev: "Trước",
   paginationNext: "Sau",
   listRange: "Hiển thị {{from}}–{{to}} trên {{total}}",