Attractor detail sharpness

The attractor accumulates its trails into an offscreen grid sized to what it is drawing into, up to 2560x1440 — so at 1080p the filaments are pixel-crisp rather than upscaled from the old fixed 640x360 grid. Nothing to bind: it follows the window. Two authoring consequences: size now reads finer at high resolution (a value tuned when the field was soft may look thin — nudge it up), and turning trails or kaleido_* on routes it through those stages’ grid instead. Since Plan 0033 that grid follows the render target too, so stacking them no longer softens the attractor the way it did against the old fixed 1280x720 — the two caps still differ, so a very large window resolves the attractor alone slightly finer.