Winter wind: flow-field particles (igloo-style)…

Details

Wind rework:
- The tapered ribbon 'gust' streaks read like rain/tadpoles. Replace with
  a proper flow-field particle system on a dedicated canvas: hundreds of
  blown-snow particles stream along the curl-noise wind and leave fading
  trails (destination-out), so the wind reads as coherent, swirling
  flowing snow (wind-map / igloo aesthetic). Single-path stroke + one
  composite per frame keeps winter at 60fps.
- Winter layers simplified to falling snow + snowflakes + rare shower;
  the wind layer carries the 'visible wind'. Theme-aware (white on dark,
  slate-blue on cream).
Weather toggle:
- New button beside the dark/light toggle (cloud-with-drizzle icon, shows
  a slash when off) turns the weather animation on/off; persists in
  localStorage; instantly clears or restores the canvas.

Files changed (3)