moved session lib to $lib dir

src/lib/session.js

@@ -0,0 +1,19 @@
+export function getSessionKey() {
+    const match = document.cookie.match(/(^| )sessionKey=([^;]+)/);
+    return match ? match[2] : null;
+}
+
+export function setSessionKey(sessionKey) {
+    document.cookie = `sessionKey=${sessionKey}; path=/; max-age=604800`;
+}
+
+export function redirectToLogin() {
+    const currentPath = encodeURIComponent(window.location.pathname);
+    window.location.href = `/login?returnUrl=${currentPath}`;
+}
+
+export function ensureAuthenticated() {
+    if (!getSessionKey()) {
+        redirectToLogin();
+    }
+}