Sun rays: brighter, and a hard 3 degree threshold with a 2 s fade

Owner 2026-08-03: «лучи поярче, иногда плохо видны. Убрать плавное
затухание — появляться и исчезать анимацией в 2 секунды при переходе
через 3 градуса над горизонтом».

RAY_MAX_ALPHA 0.18 -> 0.30: checked against both hard cases, a daylight
sun on white paper and a low sun over the dark glow canvas
(demo/shot_sun_bright.mjs writes the pair).

The gradual ramp-in over the first ~2 degrees is gone. rayAlpha() is now a
threshold: 0 below RAY_ELEVATION_MIN (3), rayPeakAlpha(cloud) at or above
it — cloud cover stays the only multiplier. Crossing it animates the
LAYER, never the geometry: <g class='sunlayer'> fades in/out over exactly
RAY_FADE_MS = 2 s (hp-sunfade-in / hp-sunfade-out), and the card keeps the
group mounted with .out for those two seconds so the dissolve can play at
all. prefers-reduced-motion skips it. Every other reason to drop the
wedges — editor, feature off, night, rain — stays instant.

Units: rayAlpha rewritten (ramp tests dropped), raysVisible/rayPeakAlpha/
RAY_MAX_ALPHA covered. Smoke: smoke_sun gains a threshold section (8 of
its checks fail on the previous build). docs/SUN.md + TESTING.md updated.

src/styles.ts

@@ -1111,6 +1111,30 @@ export const cardStyles = css`
        sense rings, the vacuum puck's 2.2s period, and a moderate opacity so
        two curtains travelling at once never turn into a strobe. The plate
        itself stays neutral — yellow means «включено», nothing else. */
+    /* Sun wedges (docs/SUN.md). The layer is present ONLY above the 3°
+       threshold; crossing it fades the whole layer in or out over EXACTLY
+       2 s (owner 2026-08-03 — RAY_FADE_MS in src/sun.ts must match). The
+       geometry is untouched: this is a plain opacity animation on the group,
+       so overlapping wedges keep their own blending while it plays. */
+    .sunlayer {
+      animation: hp-sunfade-in 2s linear both;
+    }
+    .sunlayer.out {
+      animation: hp-sunfade-out 2s linear both;
+    }
+    @keyframes hp-sunfade-in {
+      from { opacity: 0; }
+      to { opacity: 1; }
+    }
+    @keyframes hp-sunfade-out {
+      from { opacity: 1; }
+      to { opacity: 0; }
+    }
+    @media (prefers-reduced-motion: reduce) {
+      /* no fade at all: the rays are simply there or simply gone */
+      .sunlayer, .sunlayer.out { animation: none; }
+      .sunlayer.out { opacity: 0; }
+    }
     .dev.covermove::after {
       content: '';
       position: absolute;