Make the image optional for WordPress posts too

Some blog posts just don't have one. WordPressPublisher no longer
rejects publishing a type=blog post without image_url — it uploads
and attaches it as the featured image when present, and simply skips
that step (no featured_media set) otherwise.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/Support/Publishing/WordPressPublisher.php

@@ -20,10 +20,6 @@ class WordPressPublisher implements Publisher
             return PublishResult::rejected("Post {$post->id} has no title, required to publish to WordPress.");
         }
 
-        if (! $post->image_url) {
-            return PublishResult::rejected("Post {$post->id} has no image, required to publish to WordPress.");
-        }
-
         $site = $post->site;
 
         if ($site->cms_type !== 'wordpress') {
@@ -34,20 +30,25 @@ class WordPressPublisher implements Publisher
             return PublishResult::rejected("Site '{$site->name}' is missing WordPress credentials.");
         }
 
-        $mediaId = $this->uploadFeaturedImage($post, $site);
+        $payload = [
+            'title' => $post->title,
+            'content' => $post->body,
+            'status' => 'publish',
+        ];
 
-        if ($mediaId instanceof PublishResult) {
-            return $mediaId;
+        if ($post->image_url) {
+            $mediaId = $this->uploadFeaturedImage($post, $site);
+
+            if ($mediaId instanceof PublishResult) {
+                return $mediaId;
+            }
+
+            $payload['featured_media'] = $mediaId;
         }
 
         try {
             $response = Http::withBasicAuth($site->wp_username, $site->wp_app_password)
-                ->post(rtrim($site->url, '/').'/wp-json/wp/v2/posts', [
-                    'title' => $post->title,
-                    'content' => $post->body,
-                    'status' => 'publish',
-                    'featured_media' => $mediaId,
-                ]);
+                ->post(rtrim($site->url, '/').'/wp-json/wp/v2/posts', $payload);
         } catch (ConnectionException $e) {
             return PublishResult::failed("could not connect to site: {$e->getMessage()}");
         }