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/i18n/locales/zh-Hant.json

@@ -1614,7 +1614,6 @@
   "Thermal": "熱成像",
   "Anime": "動漫",
   "Noir": "黑白",
-  "Snow": "雪景",
   "Current cockpit vision style: {style}. Activate for next style.": "當前座艙視覺樣式：{style}。點擊可切換到下一個樣式。",
   "Current style: {style} — click for next": "當前樣式：{style}——點擊切換到下一個",
   "Collapse Contact panel": "收起目標面板",
@@ -2523,7 +2522,6 @@
   "Simulate FLIR-style thermal contrast. Turn up Ironbow for color.": "模擬 FLIR 風格的熱成像對比。調高 Ironbow 可顯示色彩。",
   "Apply bright cel-shaded color and illustrated outlines.": "應用明亮的賽璐珞色彩和插畫輪廓線。",
   "Apply high-contrast monochrome film-noir grading.": "應用高對比度的黑白電影風格調色。",
-  "Add a cold, snowy whiteout treatment to the scene.": "為場景添加寒冷的暴雪白化效果。",
   "MAP SOURCE": "地圖源",
   "Map source": "地圖源",
   "Style": "樣式",