Expand webmentions source and target columns to text

Long brid.gy Bluesky source URLs exceed 255 characters, causing
SQLSTATE[22001] errors. Changed source and target from varchar(255)
to text (no performance impact in PostgreSQL).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

database/migrations/2026_03_14_000000_expand_webmentions_source_target_to_text.php

@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+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('webmentions', function (Blueprint $table) {
+            $table->text('source')->change();
+            $table->text('target')->change();
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table('webmentions', function (Blueprint $table) {
+            $table->string('source')->change();
+            $table->string('target')->change();
+        });
+    }
+};