feat: add published_url column to posts

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

database/migrations/2026_07_19_134706_add_published_url_to_posts_table.php

@@ -0,0 +1,22 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    public function up(): void
+    {
+        Schema::table('posts', function (Blueprint $table) {
+            $table->string('published_url')->nullable()->after('scheduled_at');
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table('posts', function (Blueprint $table) {
+            $table->dropColumn('published_url');
+        });
+    }
+};