Traders come through the portal and sell rune plans, rare creatures, wood and mana

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

docs/ROADMAP.md

@@ -78,7 +78,9 @@ login; the menu page *Achievements*), room levels 2 and 3 (researched in the lib
 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) and wild beasts (`src/beasts.rs`:
 dens of cave bears and giant beetles in the caverns of bigger random maps; neutral like the dwarves; beaten while
-a prison has room, a beast gives in and joins).
+a prison has room, a beast gives in and joins), traders (`src/traders.rs`: every ~10 minutes in single player a
+merchant waits a minute at an own portal; a click with the hand buys rune plans, an ember wyrm, a chainbreaker,
+wood or a mana potion) and seasons (snow above ground in winter, pumpkins at Halloween, from the real date).
 
 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