refactor: transition to struct-of-arrays ECS architecture

- Replace individual Entity structs with centralized component slices in Game struct (SoA layout).
- Implement bitmask-based component lookup (CM_Position, CM_Move, etc.).
- Convert logic from object-oriented Update() methods to standalone Systems (UpdateMoveSystem, UpdateGatherSystem, UpdateSpawnSystem).
- Update rendering, selection, and input handling to iterate over component arrays.

1 files changed, 3 insertions, 0 deletions

diff --git a/ecs/entity.go b/ecs/entity.go
new file mode 100644
index 0000000..636470c
--- /dev/null
+++ b/ecs/entity.go
@@ -0,0 +1,3 @@
+package ecs
+
+type Entity int