SNAKE game v0.3: round screen, swipe control

- 16x16 grid, 320px board centered on round 466 screen, designWidth 466
- pure snake logic in src/common/snake.js (step/turn/rotateDir/spawnFood, TDD'd)
- for-directive segment rendering, show-gated game-over overlay, 300ms tick
- swipe direction input (crown rotation confirmed unsupported on Vela S4)
- tests: snake logic + page wiring

src/app.ux

@@ -0,0 +1,10 @@
+<script>
+export default {
+  onCreate() {
+    console.log('Hello Vela app created')
+  },
+  onDestroy() {
+    console.log('Hello Vela app destroyed')
+  }
+}
+</script>