System Flow Mapper

Reproduce, on any project, a three-part deliverable:

1. $DOCS_DIR/SYSTEM_FLOW.md — the source-of-truth technical map (how data moves, what each actor can do, the data model, async paths, and a tech-debt list).
2. $DOCS_DIR/system-flow.html — a self-contained, fully-offline, jargon-free visual companion for non-technical readers.
3. $DOCS_DIR/system-flow-technical.html — a self-contained, fully-offline, interactive technical reference: searchable endpoint cards with method badges and role chips, actor-scoped sidebar navigation, sequence diagrams, and a light/dark toggle. For engineers and reviewers.

$DOCS_DIR is docs/system-flow/ inside the analyzed project (computed in Step 0c).