Show AC on each tracker row

Combatant snapshots armor_class from the enemy when added (like maxHp),
shown as an "AC n" pill next to the name for quick hit checks. Migration
backfills existing combatants from their enemy.

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

migrations/Version20260906173325.php

@@ -0,0 +1,31 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DoctrineMigrations;
+
+use Doctrine\DBAL\Schema\Schema;
+use Doctrine\Migrations\AbstractMigration;
+
+/**
+ * Auto-generated Migration: Please modify to your needs!
+ */
+final class Version20260906173325 extends AbstractMigration
+{
+    public function getDescription(): string
+    {
+        return 'Snapshot armor class onto each combatant';
+    }
+
+    public function up(Schema $schema): void
+    {
+        $this->addSql('ALTER TABLE combatant ADD armor_class SMALLINT DEFAULT 10 NOT NULL');
+        $this->addSql('UPDATE combatant c JOIN enemy e ON c.enemy_id = e.id SET c.armor_class = e.armor_class');
+        $this->addSql('ALTER TABLE combatant ALTER armor_class DROP DEFAULT');
+    }
+
+    public function down(Schema $schema): void
+    {
+        $this->addSql('ALTER TABLE combatant DROP armor_class');
+    }
+}