Add a Publisher abstraction and queued job to publish from the UI

Introduce Publisher/PublisherManager (WordPress + Reddit implementations)
so publishing logic is shared between the CLI, the queue, and future
network integrations. Add a "Publish" button on the Posts page that
dispatches PublishPostJob instead of blocking the request — Reddit's
publisher shells out to the existing Playwright sidecar and can take
tens of seconds, so it can't run synchronously in a web request.

Adds a `target` field (e.g. subreddit) and `publishing` status to Post,
plus a `publish_error` field so failures surface in the UI. Refactors
posts:publish to delegate to WordPressPublisher without changing its
CLI output contract (existing tests pass unchanged).

Also fixes two bugs found along the way: UpdatePostRequest was silently
dropping `published_url` from PATCH requests (never in its validation
rules, despite AI_API.md documenting it), and three Livewire index-page
tests were broken by the earlier auth change (never re-run after adding
the `auth` middleware) since they hit routes via HTTP without a logged-in
user.

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

app/Jobs/PublishPostJob.php

@@ -0,0 +1,53 @@
+<?php
+
+namespace App\Jobs;
+
+use App\Models\Post;
+use App\Support\Publishing\PublisherManager;
+use Illuminate\Bus\Queueable;
+use Illuminate\Contracts\Queue\ShouldQueue;
+use Illuminate\Foundation\Bus\Dispatchable;
+use Illuminate\Queue\InteractsWithQueue;
+use Illuminate\Queue\SerializesModels;
+use Illuminate\Support\Facades\Log;
+
+class PublishPostJob implements ShouldQueue
+{
+    use Dispatchable, InteractsWithQueue, Queueable, SerializesModels;
+
+    public int $timeout = 150;
+
+    public function __construct(public readonly int $postId) {}
+
+    public function handle(PublisherManager $publishers): void
+    {
+        $post = Post::with(['site', 'socialAccount'])->find($this->postId);
+
+        if (! $post) {
+            return;
+        }
+
+        $publisher = $publishers->resolve($post);
+
+        if (! $publisher) {
+            $post->update(['status' => 'draft', 'publish_error' => "No publisher available for post type '{$post->type}'."]);
+
+            return;
+        }
+
+        $result = $publisher->publish($post);
+
+        if ($result->success) {
+            $post->update(['status' => 'published', 'published_url' => $result->url, 'publish_error' => null]);
+
+            return;
+        }
+
+        $post->update([
+            'status' => $result->attempted ? 'failed' : 'draft',
+            'publish_error' => $result->error,
+        ]);
+
+        Log::error('post publish failed', ['post_id' => $post->id, 'error' => $result->error]);
+    }
+}