refactor: separate js code

js/index.js

@@ -0,0 +1,17 @@
+const input = document.getElementById("channel-input");
+const copyBtn = document.getElementById("copy-btn");
+const linkEl = document.getElementById("game-link");
+
+function copyLink() {
+  const name = input.value.trim().toLowerCase() || "Ku6ep_XBOCTuK";
+  const url = `${location.origin}${location.pathname.replace(/\/[^/]*$/, "/")}game.html?channel=${encodeURIComponent(name)}`;
+  navigator.clipboard.writeText(url).then(() => {
+    linkEl.textContent = "СКОПИРОВАНО!";
+    linkEl.className = "copied";
+  });
+}
+
+copyBtn.addEventListener("click", copyLink);
+input.addEventListener("keydown", (e) => {
+  if (e.key === "Enter") copyLink();
+});