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.

server/providers/openai/instructions.js

@@ -46,7 +46,7 @@ function realtimeInstructions(
     // string is the whole rollback.
     'NAMED VIEWS are shorthand for tool calls you already have — there is no "mode" tool for them. Treat ONLY these as the shorthand: "infrastructure mode" / "the infrastructure view" / "show me global infrastructure" means three set_layer_visibility calls (local-datacenters, local-dams, telegeography-submarine-cables) plus zoom_to_globe; "environmental mode" / "earth watch" / "active events", said as the name of a view, means set_layer_visibility for local-firms and earthquakes plus zoom_to_globe. Anything vaguer is NOT this shorthand — an open-ended question about the world or the news is an ordinary question: answer it, or use analyst_query over the layers already on. Never switch a whole view on to answer a question nobody asked to see. When you do run one, make every call before speaking, then give one confirmation naming the resulting state; if the fires layer comes back unavailable because no FIRMS key is configured, say so plainly — the earthquakes still loaded. "Live contacts" and "space missions" are NOT this pattern: they stay set_context_mode{mode:"contacts"} and set_context_mode{mode:"space-missions"}.',
     'For visual filter requests, call set_visual_style with one of the allowed style IDs.',
-    'SHIPS vs STYLES: "vessels" is easily heard as "visuals". "Show me vessels", "turn on vessels", "the vessels", "visuals" or "vestibules" said WITHOUT a style name means the ships layer: set_layer_visibility{layerId:"ais-live-vessels"}, exactly as "ships" or "boats" does. Call set_visual_style only when the user names a style (retro/CRT, surveillance/night vision, thermal, anime, noir, snow, normal) or says filter, effect or look. Never turn on a different data layer (such as fires) for a ships request.',
+    'SHIPS vs STYLES: "vessels" is easily heard as "visuals". "Show me vessels", "turn on vessels", "the vessels", "visuals" or "vestibules" said WITHOUT a style name means the ships layer: set_layer_visibility{layerId:"ais-live-vessels"}, exactly as "ships" or "boats" does. Call set_visual_style only when the user names a style (retro/CRT, surveillance/night vision, thermal, anime, noir, normal) or says filter, effect or look. Never turn on a different data layer (such as fires) for a ships request.',
     'Disambiguation table — basemap vs layer vs style: basemap switching requires an explicit stack name — "Bing aerial" means set_map_stack bing-aerial, "aerial with labels" means bing-labels, "OSM"/"road map" means osm, "Esri"/"Esri imagery" means esri-imagery, "Google 3D"/"photorealistic" means photoreal. Any other mention of "satellite" or "satellites" means the satellites DATA LAYER via set_layer_visibility, never a basemap — except "recent/latest satellite imagery" (the recent-imagery layer) and "weather satellite"/clouds (weather-satellite). "surveillance"/"night vision"/"thermal" are visual STYLES via set_visual_style.',
     'HUD requests ("hud on/off", "switch to operator/minimal/tactical/cyber layout") use set_hud. Detection requests ("detection on", "dense mode", "balanced mode", "sparse mode", "set density to 25", "use weighted allocation") use set_detection. Density snaps to 0/25/50/75/100 and derives Sparse/Balanced/Dense; panoptic is a legacy alias for Dense.',
     'Cyber sonar requests use set_cyber_sonar: enabled, rings, rangePct, intensityPct (Power), opacityPct, sectorDeg. For settings questions read get_current_view_state.controls.hud.sonar. Sonar is not detection. Do not silently switch themes, reveal the HUD or enable sonar when changing a slider. If the user explicitly requests Cyber plus sonar settings, call set_hud first, wait for success, then set_cyber_sonar. Confirm returned values; mapSweepActive and contactSweepActive distinguish saved settings from active map effects, including in Cockpit or reduced motion. Do not claim visible contacts solely because enabled is true.',