chore: stage all in-progress work before repo split

Web app: new entities (Image, RenderedAsset, SharedImage, Token,
DeviceImageHistory), enums, repositories, controllers, message handlers,
migrations, tests, frontend upload/library/sticker UI, Vue components.

Firmware: EPD background screen binaries + gen scripts, setup_bg header.

Infra: ddev config, test bundle, gitignore coverage dir.

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

tests/AppKernelTestCase.php

@@ -0,0 +1,44 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Tests;
+
+use App\Entity\User;
+use Doctrine\ORM\EntityManagerInterface;
+use Symfony\Bundle\FrameworkBundle\Test\KernelTestCase;
+use Symfony\Component\PasswordHasher\Hasher\UserPasswordHasherInterface;
+
+abstract class AppKernelTestCase extends KernelTestCase
+{
+    private ?EntityManagerInterface $em = null;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+        self::bootKernel();
+        $this->em = null;
+    }
+
+    protected function em(): EntityManagerInterface
+    {
+        if ($this->em === null) {
+            $this->em = static::getContainer()->get(EntityManagerInterface::class);
+        }
+        return $this->em;
+    }
+
+    protected function createUser(string $email, string $password = 'password'): User
+    {
+        $hasher = static::getContainer()->get(UserPasswordHasherInterface::class);
+
+        $user = new User();
+        $user->setEmail($email);
+        $user->setPassword($hasher->hashPassword($user, $password));
+
+        $this->em()->persist($user);
+        $this->em()->flush();
+
+        return $user;
+    }
+}