* fix(llm): prevent UTF-8 panic in line_bounds() (fixes#1669)
`line_bounds()` used `text[..pos]` slicing which panics when `pos`
lands inside a multi-byte UTF-8 character. This happens when
`end.saturating_sub(1)` in `is_recoverable_tool_call_segment()` steps
back into a multi-byte char like emoji.
Fix: clamp `pos` to `text.len()` and walk backward to the nearest
char boundary before slicing. Add 5 regression tests covering
mid-char positions, emoji boundaries, and out-of-bounds pos.
Also fix pre-existing clippy `unnecessary_sort_by` warnings in
web gateway handlers.
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via [Happy](https://happy.engineering)
Co-Authored-By: Claude <[email protected]>
Co-Authored-By: Happy <[email protected]>
* test: assert expected values in line_bounds UTF-8 tests
Address Gemini review: strengthen regression tests to verify correct
return values (not just absence of panic) when pos lands mid-char.
Generated with [Claude Code](https://claude.ai/code)
via [Happy](https://happy.engineering)
Co-Authored-By: Claude <[email protected]>
Co-Authored-By: Happy <[email protected]>
---------
Co-authored-by: willamhou <[email protected]>
Co-authored-by: Claude <[email protected]>
Co-authored-by: Happy <[email protected]>
