Turn-ending provider errors rendered inline through
AssistantMessageComponent#appendErrorBlock, capped at 8 lines with no
setExpanded method, so isExpandable filtered the component out of the
Ctrl+O tool-output expansion and the truncated tail was unreachable in
the live TUI (full text was persisted but not shown).
- Add setExpanded to AssistantMessageComponent; when expanded the error
block renders the full body (tabs replaced, blank lines preserved,
Text word-wraps to width).
- Collapsed view appends a dim "+N more lines (Ctrl+O to expand)" hint so
the truncation and its remedy are discoverable.
- Only re-render on toggle when the last render produced a truncatable
error block, so expansion skips ordinary turns.
Fixes#6555
roboomp
104c3ad218