* fix: stop stripping the word 'assistant' from rendered text
The QWEN_BARE_MARKER_RE regex in both the Python backend (tool_parsing.py)
and JS frontend (chatRenderer.js) was matching any standalone occurrence of
the word 'assistant' separated by any whitespace, then replacing it with a
space. This caused normal English uses like 'Home assistant' to render as
'Home '.
Fixed by narrowing the word-boundary check from [\t\r\n ] (any whitespace)
to [\r\n] (line boundaries only), so only Qwen-format role-token leaks
(where 'assistant' appears alone on a line) are stripped.
* fix(tests): update bare-marker test expectations for #5971
Move 'x assistant y' from STRIPPED to KEPT (mid-sentence must survive).
Add 'Before\nassistant\nAfter' to STRIPPED (bare-marker on own line).
* fix(ui): strip whitespace-padded assistant role markers
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Co-authored-by: samy <samy@users.noreply.github.com>
Co-authored-by: Alexandre Teixeira <alexandremagteixeira@gmail.com>
