feat: enhance HTML output with collapsible tools and sidebar stats

- Make terminal blocks fully collapsible (like diff blocks)
- Add line counts to terminal and diff headers
- Show +added/-removed separately in diff headers (with colors)
- Add hover effect on tool blocks (subtle border highlight)
- Extract more metadata from JSONL: model, CLI version, git branch,
  duration, and token usage (input/output/cache)
- Display new metadata in sidebar with proper formatting
- Fix line count wrapping with nowrap

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: vtemian