fix: sync context panel iframe themes

Keeps embedded sessions aligned with parent theme
Prevents iframe reloads on theme changes
Supports theme hotkeys from focused iframes

packages/ui/src/contexts/theme-embedded-bootstrap.ts

@@ -0,0 +1,23 @@
+export const readEmbeddedThemeSearchParams = (): URLSearchParams | null => {
+  if (typeof window === 'undefined') {
+    return null;
+  }
+  const params = new URLSearchParams(window.location.search);
+  return params.get('ocPanel') === 'session-chat' ? params : null;
+};
+
+const getSystemPreference = (): boolean => {
+  if (typeof window === 'undefined') {
+    return true;
+  }
+  return window.matchMedia('(prefers-color-scheme: dark)').matches;
+};
+
+export const getInitialSystemPreference = (): boolean => {
+  const embeddedParams = readEmbeddedThemeSearchParams();
+  const embeddedVariant = embeddedParams?.get('themeVariant');
+  if (embeddedVariant === 'dark' || embeddedVariant === 'light') {
+    return embeddedVariant === 'dark';
+  }
+  return getSystemPreference();
+};