Staff report: CSP frame-ancestors + frame-mode + WebForm-mw Civi extension

App side:
- Per-route CSP: /staff/report now sets frame-ancestors 'self'
  <CIVI_BASE_URL origin> and drops X-Frame-Options so the CiviCRM
  extension can iframe it. All other routes keep frame-ancestors
  'none' + X-Frame-Options: DENY via a path-negation source.
- Staff page recognises ?frame=1 and renders without SiteHeader/
  SiteFooter so it fills the iframe cleanly.
- StaffReportView posts its scrollHeight to the parent window via
  postMessage when framed; the Civi tab listens and auto-resizes
  the iframe (no nested scrollbar). Anchor strip drops its sticky
  positioning in frame mode since there's no internal scroll.

CiviCRM extension (civi-extension/webform-mw/, key webform-mw):
- info.xml + main hook file (webform_mw.php) implementing
  hook_civicrm_tabset to add an 'Engagement Report' tab to
  Organization contact-view pages.
- CRM/WebformMw/Page/Tab.php + Smarty template render an iframe
  pointing at <WEBFORM_MW_APP_URL>/staff/report?org=<cid>&key=&frame=1,
  with a postMessage listener that validates event.origin against
  the configured app URL before resizing.
- Config via PHP constants in civicrm.settings.php (WEBFORM_MW_APP_URL,
  WEBFORM_MW_STAFF_KEY) or matching env vars. Help banner shown when
  unconfigured.
- README documents install, config, behaviour, security caveats.

civi-extension/webform-mw/xml/Menu/webform_mw.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="iso-8859-1" ?>
+<menu>
+  <item>
+    <path>civicrm/contact/view/engagement-report</path>
+    <title>Engagement Report</title>
+    <page_callback>CRM_WebformMw_Page_Tab</page_callback>
+    <access_arguments>access CiviCRM</access_arguments>
+  </item>
+</menu>