Generates a rich, self-contained HTML session report (dark-themed, inline
CSS/SVG, no network dependencies) plus a concise Markdown companion for LLM
re-ingestion, written to $XDG_DOCUMENTS_DIR/session-reports/.
The report includes: a numbered problem→investigation→resolution timeline, a detailed tool-use log (including false starts), inline SVG architecture diagrams and CSS bar charts, a root-cause table, and overall observations. Complex visuals are render-verified headlessly before delivery — via