Agent Skills: lc-algo-demo

Add or edit an algorithm visualizer under algo_demo/ against the shared contract the other 36 pages already obey — colours read from the VIZ palette and never hardcoded, no re-implementation of the devicePixelRatio canvas wrapper, the step trace written in the three shapes createLogger renders as structure, the trace in its own full-width panel below the canvas, and `draw = VIZ.repaintable(draw)` for any draw() that takes arguments. Use when asked to add a visualizer, animate an algorithm, build a demo page, or change something that should look the same on every visualizer. Triggers - "add a visualizer for Dijkstra", "/lc-algo-demo trie", "animate the sliding window", "the trace is unreadable on the segment tree page".