Fixes#3869: empty legacy three-dot thinking spinners piled up as stale
rows after the agent finished thinking. The live-to-final redesign (#3401)
made the thinking-card-row wrapper class unconditional, which broke
finalizeThinkingCard()'s dots-only detection — it treated the wrapper class
itself as a "has content" signal, so the dots-only removal branch went dead.
Narrow hasContent to the actual .thinking-card element so dots-only spinners
are removed on finalize while real Worklog Thinking Cards are preserved.
Includes #3869 regression coverage (brace-walks finalizeThinkingCard, asserts
the narrowed check + that real thinking cards are not removed).
Co-authored-by: nesquena-hermes <[email protected]>
Co-authored-by: franksong2702 <franksong2702@users.noreply.github.com>
