004a8f19c1
Draw.io / Figma style: while dragging a node, show dashed cyan guide lines when its edges (left / center / right / top / middle / bottom) align with another node's, and snap the position to the matched line within a configurable threshold. - utils/alignment.ts: pure snap math, returns delta + guide segments. Same-size boxes show all aligned guides simultaneously. - canvas/AlignmentGuides.tsx: SVG overlay locked to the React Flow viewport (panned/zoomed correctly). - hooks/useAlignmentGuides.ts: wires onNodeDrag/onNodeDragStop, applies snap via setNodes, listens for Alt to temporarily disable. - utils/alignmentSettings.ts: localStorage-backed prefs (enabled, threshold 2-16px) with a tiny CustomEvent pub-sub so the SettingsPanel and the drag hook stay in sync without a global store. - Sidebar settings panel: toggle + threshold slider. Multi-selection drag uses the union bounding box. Children with parentId are skipped for v1 to avoid mixing absolute and parent-relative coordinates. Hold Alt to escape snap.