Replace the WebBlock search card's head/tail collapse and expand button
with a fixed-height scroll container that lists every source the tool
returned. The model-facing side is unchanged: the seam still caps sources
at searchMaxResults and the truncated indicator stays, so model-visible
and frontend-visible sources remain identical.
Remove CHAT_WEB_MAX_SOURCES and DEFAULT_WEB_MAX_SOURCES: with scroll, the
chat row and details panel show the same full list.