Knowledge Assistant: user page + developer guide New pair for #939. The user page leads with why the assistant is allowed to refuse, since that is the design decision the whole feature rests on. The developer guide carries the colour-keyed file table and documents the three things nobody would guess: the buffered verdict line, overlap-coefficient similarity with a two-token floor (not Jaccard), and single-linkage clustering - the last two both forced by tests/knowledge-gaps failing. Also a section on Knowledge.md and both pages in _Sidebar.md.