- Cache parseSubBlocks per block (only reparse when content changes)
- Cache highlightedHtml results (code+language key)
- Prevents expensive KSyntaxHighlighting and regex on every render
- Also fixes scroll loop with _scrolling guard
Replace flat TextArea chat view with structured ListView:
- ChatBlockModel parses raw chat text into typed blocks (user,
assistant, reasoning, call, tool, error, info)
- Sub-blocks parsed from markdown: prose, fenced code, diffs
- Code blocks rendered with KSyntaxHighlighting (auto light/dark theme)
- Diff blocks with red/green line coloring
- Copy button on code and diff blocks
- File paths linkified and clickable (opens with xdg-open)
- Reasoning/call/tool blocks collapsible (click to expand)
- User blocks highlighted with subtle accent background
- Error blocks in red
- Scroll pinning preserved (auto-scroll when at bottom)