Initial release: diagram-design v1.0

Thirteen editorial diagram types (architecture, flowchart, sequence,
state, ER, timeline, swimlane, quadrant, nested, tree, layers, venn,
pyramid) as self-contained HTML files with inline SVG.

Progressive disclosure: lean SKILL.md points to per-type references.
Neutral stone+rust default skin, first-run gate that prompts users
to customize the style guide from their own website, URL-based
onboarding, annotation-callout primitive, sketchy filter variant,
live gallery at assets/index.html.

references/type-swimlane.md

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+# Swimlane
+
+**Best for:** cross-functional processes, RACI-style flows, vendor handoffs, multi-team shipping workflows.
+
+## Layout conventions
+- Horizontal lanes (or vertical columns) — one per actor/team. Label each lane in the left margin (or top) with a Geist Mono eyebrow.
+- Lane dividers: 1px hairlines.
+- Process steps are rectangles placed inside the lane of the actor performing them; arrows show flow.
+- Handoffs (arrows crossing lane boundaries) are the most important edges — consider coral on the handoff that introduces the most coupling or latency.
+- Don't force equal step count per lane; a lane with one step is fine.
+
+## Anti-patterns
+- Lanes without labels.
+- A step drawn across two lanes (pick one owner).
+- Arrows that snake back and forth — reorder steps so the flow is mostly straight.
+
+## Examples
+- `assets/example-swimlane.html` — minimal light
+- `assets/example-swimlane-dark.html` — minimal dark
+- `assets/example-swimlane-full.html` — full editorial