feat(snake): implement snake game with pure game logic, renderer, and IPC-based main loop

crates/apps/snake/src/tests/renderer.rs

@@ -0,0 +1,32 @@
+use crate::game::Snake;
+use crate::renderer::{render, RenderCommand};
+
+#[test]
+fn render_produces_commands() {
+    let snake = Snake::new();
+    let mut commands = [RenderCommand { x: 0, y: 0, w: 0, h: 0, color: 0 }; 64];
+    let count = render(&snake, &mut commands);
+    // background + border + food + 3 body segments = 6
+    assert!(count >= 6);
+}
+
+#[test]
+fn first_command_is_background() {
+    let snake = Snake::new();
+    let mut commands = [RenderCommand { x: 0, y: 0, w: 0, h: 0, color: 0 }; 64];
+    render(&snake, &mut commands);
+    assert_eq!(commands[0].x, 0);
+    assert_eq!(commands[0].y, 0);
+    assert!(commands[0].w > 0);
+    assert!(commands[0].h > 0);
+}
+
+#[test]
+fn food_is_rendered() {
+    let snake = Snake::new();
+    let mut commands = [RenderCommand { x: 0, y: 0, w: 0, h: 0, color: 0 }; 64];
+    let count = render(&snake, &mut commands);
+    // Food is command index 2 (after bg and border)
+    assert!(count > 2);
+    assert_eq!(commands[2].color, 0xFF0040);
+}