Preserve preview harness, editor, email and task improvements

Snapshot current maintainer-preview application changes and regression fixtures for integration into lab. Excludes local runtime data, evaluation outputs and source backups. Focused Python regression selection: 140 passed; full suite not certified.

static/js/tourHintDismiss.js

@@ -0,0 +1,26 @@
+import { registerEscapeLayer } from './escMenuStack.js';
+
+// Give every tutorial hint the same button, timeout, and Escape lifecycle.
+// The global Escape arbiter closes one layer before its underlying window.
+export function bindTourHintDismiss(hint, { timeout, fade = 280, onDismiss } = {}) {
+  let closed = false;
+  let timer;
+  const button = hint.querySelector('.tour-hint-dismiss');
+  const unregister = registerEscapeLayer(close, () => hint.isConnected && !closed);
+
+  function close() {
+    if (closed) return;
+    closed = true;
+    clearTimeout(timer);
+    unregister();
+    button?.removeEventListener('click', close);
+    hint.classList.add('tour-hint-out');
+    setTimeout(() => hint.remove(), fade);
+    onDismiss?.();
+  }
+
+  button?.addEventListener('click', close);
+  if (timeout > 0) timer = setTimeout(close, timeout);
+  hint._dismiss = close;
+  return close;
+}