Weather above ground: rain puts out fires, fog shortens sight, storms strike with lightning

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/ROADMAP.md

@@ -134,5 +134,8 @@ grid), guard and attack markers (shields and swords), savegames with the game st
    level), Warlord (creatures +5% damage, -5% damage taken), Warlock (mana +15%, spells -6%), Merchant (wages
    -6%, treasure +6%); 5 levels each. The "Master" button (number of free points, pulsing) opens the window.
    AI masters spend their points themselves; per game, carried over in the campaign and co-op runs.
-5. **Weather above ground** - rain (puts out fire), fog (less sight), storms (lightning in trees and units).
+5. **Weather above ground** (done, v202611-00066, weather.rs) - about 60% fair, 20% rain, 12% fog, 8% storm,
+   minutes each with soft 20 s changes, only on maps with land above ground. Rain (and storms) put out burning
+   bridges and keep fire from catching; fog halves the sight of units outside; storms strike units (40 damage)
+   or trees with lightning every 6-20 s. Dimmed daylight, rain streaks, fog veils, flashes; a HUD label.
 6. **Named creatures** - names per kind and language, epithets at higher levels, memorial stones.