feat(entities): afegeix stone i column com a muros decoratius

CMakeLists.txt

@@ -52,6 +52,7 @@ set(ENTITY_SOURCES_BASE
     source/game/entities/concrete/floor_trap.cpp
     source/game/entities/concrete/hole.cpp
     source/game/entities/concrete/dust.cpp
+    source/game/entities/concrete/solid_props.cpp
 )
 
 # Entitats que criden directament símbols de Player (com WhipAttack via