refactor: extract coerce and stressorToString into util.js

static/util.js

@@ -0,0 +1,13 @@
+export function coerce(s) {
+    if (s === 'True' || s === 'Y' || s === 'on' || s === 'true') return true;
+    if (s === 'False' || s === 'N' || s === 'off' || s === 'false') return false;
+    if (s === '') return s;
+    const n = Number(s);
+    if (!isNaN(n)) return n;
+    return s;
+}
+
+export function stressorToString(s) {
+    if (!s?.groups?.length) return '';
+    return s.groups.map(g => g.join(',')).join(';');
+}