Color an Obsidian Digital Garden's graph nodes and links by their top-level folder. Use when the user wants the oleeskild/Eleventy Digital Garden graph view (local + full) to distinguish content areas by color instead of one flat theme color. Ships a build-time color injector plus optional footer legend, driven by a single folder->color map. No plugin-core edits: the stock Pixi renderer already honors node.color, so this only populates it via a one-line wrap in the user-owned _data graph hook. Trigger on: colored graph, graph colors, folder colors, color graph by folder, graph legend, digital garden graph colors.
