feat(content): demo the state engine (generator unlocks/lights the cellar)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Semesterprojekt/src/main/resources/world/rooms.yaml

@@ -9,6 +9,11 @@
     south: dungeon
   items: [letter, lamp]
   npcs: [old_man]
+  exitLocks:
+    - direction: east
+      requires: [{ flag: power_on }]
+      blocked: |
+        The cellar door is held shut by a magnetic lock — dead without power.
 
 - id: hallway
   name: Dark Hallway
@@ -40,12 +45,17 @@
     west: kitchen
   items: []
   npcs: []
+  descriptionStates:
+    - when: [{ flag: power_on }]
+      text: |
+        With the power back, a bare bulb buzzes overhead, revealing
+        shelves of dusty jars along the far wall.
 
 - id: dungeon
   name: Dungeon
   description: |
-    A dark, damp room.
+    A dark, damp room. A rusty generator squats in the corner.
   exits:
     north: kitchen
-  items: []
+  items: [generator]
   npcs: []