fix(security): harden external-link opening (protocol allow-list + noopener)

URLs reached window.open from user/server-controlled content without a protocol check or noopener, allowing reverse-tabnabbing and (for the chat link handler) a javascript:/data: href running in our origin.

- add isSafeExternalUrl() (http/https only) + tests; gate the chat link opener (useOnClickChat) and external photo opener with it

- SanitizeHtml: afterSanitizeAttributes hook forces rel="noopener noreferrer" on any target=_blank anchor (overrides attacker-supplied rel)

- add noopener,noreferrer to the remaining window.open(_blank) sites (YouTube share, external photo, guide forum link); drop a stray console.log

src/components/guide-tool/GuideToolView.tsx

@@ -321,7 +321,7 @@ export const GuideToolView: FC<{}> = props =>
                 return;
             case 'forum_link':
                 const url: string = GetConfigurationValue<string>('group.homepage.url', '').replace('%groupid%', GetConfigurationValue<string>('guide.help.alpha.groupid', '0'));
-                window.open(url);
+                window.open(url, '_blank', 'noopener,noreferrer');
                 return;
         }
     }, [ isHandlingBullyReports, isHandlingGuideRequests, isHandlingHelpRequests, simpleAlert ]);