fix: prevent non-combat room repeated rewards during descent (Issue #382)

- Wrap library XP grant in progress < required guard so completed rooms don't grant XP every tick
- Add early return in treasure room tick when progress >= required to skip loot processing
- Initialize non-combat rooms (library, treasure, recovery) during descent in onEnterRoomDescend
- Add regression test file: non-combat-room-reward-guards.test.ts (8 tests)

src/lib/game/stores/combat-descent-actions.ts

@@ -214,6 +214,17 @@ export function onEnterRoomDescend(get: GetFn, set: SetFn): void {
         });
       }
     }
+
+    // Initialize non-combat rooms during descent so they have proper progress tracking
+    if (s.currentRoom.roomType === 'library') {
+      onEnterLibraryRoom(get, set);
+    } else if (s.currentRoom.roomType === 'recovery') {
+      onEnterRecoveryRoom(get, set);
+    } else if (s.currentRoom.roomType === 'treasure') {
+      onEnterTreasureRoom(get, set);
+    } else if (s.currentRoom.roomType === 'puzzle') {
+      onEnterPuzzleRoom(get, set);
+    }
     return;
   }