Previous commit (b5aa6ffd) dropped top_k for every Anthropic call,
but only Claude 4.7 (Opus/Sonnet/Haiku) actually rejects it. 4.6, 4.5,
and the 3.x line still accept top_k and use it as documented.
Backend: _stream_anthropic matches the model id against
^claude-(opus|sonnet|haiku)-4-7(-|.|$) and only strips top_k when it
hits. Every other Claude generation continues to receive the value
from the chat settings panel.
Frontend: anthropic.topK is restored to true so the Top K slider is
visible again — the backend handles the per-model drop, and the
4.7 case is silent (request still succeeds without top_k).
1e98b384e6