Random events: earthquakes, overflowing rivers, new gold veins (free games and versus, can be switched off)

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

docs/ROADMAP.md

@@ -73,7 +73,10 @@ bosses (`src/bosses.rs`: four champions of the Order lead every fifth wave - Sir
 Dame Seraphine's radiant burst, Brother Halvard's call to arms, Captain Rothgar's charge - with a health bar
 and loot), statistics (`src/stats.rs`: counters and a chart at the end of a game) and achievements
 (`src/achievements.rs`: 64 of them, kept in the browser and merged with `/api/profile` on the server after a
-login; the menu page *Achievements*). Room levels 2 and 3 will be researched in the library (per room kind).
+login; the menu page *Achievements*), room levels 2 and 3 (researched in the library once every tool is known:
++25% per level, brighter, gold trim) and random events (`src/events.rs`: earthquake, lava or water over the
+banks, a new gold vein; every 8-12 minutes in free games and versus matches, switch in the game settings; the
+host's choice goes to every client with `"events"` in the create message).
 
 1. **Random events** – earthquake (tunnels cave in), lava eruption, flood, gold vein found. Rare
    (every 8–12 minutes), free play and multiplayer only, can be switched off in the menu; in