Fix waypoint double-click: pointerdown preventDefault was suppressing dblclick; manual double-tap detection (works on touch too)

▶ Play it: Food Court Eternity → Smoke Arithmetic → Barometric Stampede — a constellation across three families — the path is the mix https://stellate.app/?genre=vaporwave&seed=6571&path=1679.4415,292.16891,1718.20526&xdur=0.046

e84c415 https://github.com/aboard-io/stellate/commit/e84c41531ae0e6dced2dec7a122a25c689e9f7cf