The watch-state About block rendered its poster whenever the URL was
non-empty, so a URL that failed to load showed the browser's broken-image
glyph with clipped alt text. The hero above already falls back on error.
A failed URL now counts as missing, matching the block's own degradation
rule. The failure is keyed by URL so a different poster gets a fresh attempt.
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
