…1701)

Document-to-memory links and actual `derives` relations were both emitted as `derives`, so they shared the same color and legend entry.

This separates structural document links into a `document` edge type, adds a dedicated theme color with `--graph-edge-document` support, and updates force-layout and level-of-detail handling to preserve existing structural behavior. The package and MCP widget legends/themes now distinguish document links from derived-memory relations.

Adds regression coverage for edge classification and validates the package plus its MCP consumer.

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