refactor(phase1.5): revert testing parameters to production values

- Reset initial snake size from 6 back to 3 segments
- Keep INITIAL_FPS at 5 (good starting speed)
- FOODS_PER_LEVEL = 2 (correct production value)
- Game now starts at normal difficulty
- Clean production-ready state
- Build and example app work correctly

src/useCursor/useCursor.ts

@@ -19,14 +19,11 @@ export function useCursor(
      const centerR = Math.floor(rows / 2);
      const centerC = Math.floor(cols / 2);
      
-     const initialBody: SnakeBody = [
-       { r: centerR, c: centerC },
-       { r: centerR + 1, c: centerC },
-       { r: centerR + 2, c: centerC },
-       { r: centerR + 3, c: centerC },
-       { r: centerR + 4, c: centerC },
-       { r: centerR + 5, c: centerC },
-     ];
+      const initialBody: SnakeBody = [
+        { r: centerR, c: centerC },
+        { r: centerR + 1, c: centerC },
+        { r: centerR + 2, c: centerC },
+      ];
     
     setSnakeBody(initialBody);
     snakeBodyRef.current = initialBody;