Store high scores per scene and add README

main.js

@@ -24,7 +24,7 @@
       id: "scene1",
       name: "Balanced (default)",
       config: {
-        gravity: 0.78,
+        gravity: 0.88,
         spawnIntervalMs: 720,
         minChain: 3,
         palette: ["#ff595e", "#ffca3a", "#8ac926", "#1982c4", "#6a4c93"],
@@ -175,11 +175,11 @@
   let gameOver = false;
   let isPaused = false;
 
-  const STORAGE_KEY = "physilinks-highscore";
+  const makeStorageKey = (sceneId) => `physilinks-highscore-${sceneId}`;
 
-  const loadHighScore = () => {
+  const loadHighScore = (sceneId) => {
     try {
-      const raw = localStorage.getItem(STORAGE_KEY);
+      const raw = localStorage.getItem(makeStorageKey(sceneId));
       const parsed = parseInt(raw, 10);
       return Number.isFinite(parsed) ? parsed : 0;
     } catch (err) {
@@ -189,7 +189,7 @@
 
   const saveHighScore = () => {
     try {
-      localStorage.setItem(STORAGE_KEY, String(highScore));
+      localStorage.setItem(makeStorageKey(currentScene.id), String(highScore));
     } catch (err) {
       // ignore write failures (private mode or blocked storage)
     }
@@ -212,6 +212,7 @@
     if (sceneSelectEl) sceneSelectEl.value = next.id;
     Object.assign(config, next.config);
     engine.gravity.y = config.gravity;
+    highScore = loadHighScore(next.id);
     rebuildSceneBodies();
     buildLegend();
     restartGame();
@@ -583,7 +584,6 @@
   if (sceneSelectEl) {
     sceneSelectEl.addEventListener("change", (e) => applyScene(e.target.value));
   }
-  highScore = loadHighScore();
   populateSceneSelect();
   applyScene(currentScene.id);
 })();