Removes redundant brain state definition

The `State` enum, along with its variants (Starting, Running, Stopping, Stopped), is no longer required for managing the brain's operational stages. This change simplifies the codebase by removing an unnecessary abstraction.

src/rustylee/build_number.txt

@@ -1 +1 @@
-140
+142

src/rustylee/src/brain/state.rs

@@ -1,7 +0,0 @@
-#[derive(PartialEq, Debug, Clone, Copy)]
-pub enum State {
-    Starting,
-    Running,
-    Stopping,
-    Stopped,
-}