README: add an editor screenshot and a link to the live demo

.gitattributes

@@ -7,3 +7,4 @@
 /phpunit.xml.dist   export-ignore
 /phpstan.neon.dist  export-ignore
 /testbench.yaml     export-ignore
+/docs/editor.png   export-ignore

README.md

@@ -8,6 +8,10 @@ A modular, Outlook-bulletproof email building, auditing, and compilation engine
 
 Build an email from 29 responsive blocks (in code, in a Filament form, or in a drag-and-drop editor), audit it before it goes out, and compile it to inlined HTML, AMP for Email, MJML, or plain text. It is a plain Laravel package: the compiler is PHP, with no Node step at send time.
 
+[![The drag-and-drop editor, with the block palette, a live email preview and the block settings panel](docs/editor.png)](https://odden.io/open-source/mail-builder)
+
+[Try the editor in your browser](https://odden.io/open-source/mail-builder): it is the one in this package, with nothing saved or sent.
+
 Requires PHP 8.3+ and Laravel 12 or 13. Maintained by [CaskStack, LLC](https://odden.io).
 
 **Status:** All 29 slot types are rendered by the compiler, described in the slot schema, and editable in both the Filament builder and the drag-and-drop editor.

src/Support/OutboundUrlGuard.php

@@ -115,11 +115,11 @@ public function isSafe(string $url): bool
 
     public static function isPublicAddress(string $address): bool
     {
-        return filter_var(
+        return (bool) filter_var(
             $address,
             FILTER_VALIDATE_IP,
             FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE | FILTER_FLAG_GLOBAL_RANGE,
-        ) !== false;
+        );
     }
 
     /**