Fix clouds3d: JS line comments inside FRAG_SRC array broke parsing

When I added the ground-texture code I left the comment as
multiple JS-line-comments ('// Horizon...') between strings.
Those are NOT inside any string, so JS sees:
  '// Horizon: ... satellite    <- opens string, never closes
  // ground texture ...           <- JS thinks these are line comments
  ...
The string stays open until the next ',, then the next string
line parses as a continuation of an unterminated string and the
whole file is rejected. Wrap the comment into one quoted string.

vendor/clouds3d.js

@@ -195,11 +195,7 @@ var FRAG_SRC = [
         // remain visible against a deep but not void-black sky.
         'float skyDarkness = nightFactor * 0.55;',
         'col = mix(col, col * (1.0 - skyDarkness), 1.0 - cloud);',
-        '// Horizon: when looking down (rd.y < 0), sample the satellite
+        '// Horizon: when looking down (rd.y < 0), sample the satellite ground texture based on ray direction. Use the horizontal component as a UV \u2014 the further off-axis, the more the texture scrolls. Adds parallax-like feel even though the ground is a flat image.',
-        // ground texture based on ray direction. Use the horizontal
-        // component as a UV — the further off-axis, the more the
-        // texture scrolls. Adds parallax-like feel even though the
-        // ground is a flat image.
         'float gmask = smoothstep(-0.02, -0.20, rd.y);',
         'vec2 gUv = vec2(rd.x * 0.5 + 0.5, -rd.y * 0.5 + 0.3);',
         'vec3 groundCol = texture2D(uGround, gUv).rgb;',