Remove the Snow visual preset

Snow is no longer offered anywhere a style can be chosen: the Visual
Presets tray, keyboard shortcut 7, the Cockpit vision carousel, and the
set_visual_style voice action. The shader and its labels go with it;
weather snowfall and the SNOW weather condition are unaffected.

Share links keep working. Snow's enum code (6) stays reserved, so a
compact or long-form link that names it opens on Normal and drops the
Snow shader parameters without reporting them as unknown. A Scene
Director shot saved with Snow plays on Normal too. Snow's frozen share
defaults matched Normal's apart from those parameters, so no other
setting in an old link changes meaning.

The legacy voice-schema pins restore Snow before hashing, so the
unchanged pins still prove nothing else moved; the complete Realtime
payload digest is re-derived.

src/data/trafficPresetStyle.js

@@ -20,7 +20,7 @@
  *    jam keeps a size bump so queues read as fat beads.
  *  - `crt` (retro): saturated primaries that survive 10-level posterization
  *    plus an all-bucket size boost to out-shout the pixel grid.
- *  - `normal` (normal/anime/snow/unknown): every lookup returns null/0 —
+ *  - `normal` (normal/anime/unknown): every lookup returns null/0 —
  *    the shipped palette and sizing apply untouched.
  *
  * Sim/uncovered dots (bucket null/'sim') are NEVER restyled under any

src/data/trafficPresetStyle.test.mjs

@@ -13,7 +13,7 @@ const luma = ([r, g, b]) => (0.299 * r + 0.587 * g + 0.114 * b) / 255;
 
 const BUCKETS = ['free', 'slow', 'jam'];
 const MONO_STYLES = ['surveillance', 'thermal', 'noir'];
-const NORMAL_STYLES = ['normal', 'anime', 'snow', 'does-not-exist', '', undefined, null];
+const NORMAL_STYLES = ['normal', 'anime', 'does-not-exist', '', undefined, null];
 
 test('profile mapping: NVG/FLIR/noir are mono, retro is crt, everything else normal', () => {
   for (const s of MONO_STYLES) assert.equal(trafficStyleProfile(s), 'mono', s);

src/data/transitPresetStyle.js

@@ -18,7 +18,7 @@
  *    black sprite with a light ring is what a hot object looks like there.
  *  - `crt` (retro): saturated per-mode colours that survive posterisation,
  *    a size boost to out-shout the pixel grid, and a thinner halo.
- *  - `normal` (normal/anime/snow/unknown): every lookup returns the shipped
+ *  - `normal` (normal/anime/unknown): every lookup returns the shipped
  *    value — mode colour, shipped size, hairline edge only.
  *
  * Brackets are a different matter. The detection canvas composites ABOVE the

src/data/transitPresetStyle.test.mjs

@@ -17,7 +17,6 @@ test('profile mapping: NVG/FLIR/noir and cockpit nvg are mono, retro is crt, eve
   for (const plain of [
     'normal',
     'anime',
-    'snow',
     'minecraft',
     '',
     null,