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>

src/Service/ShareService.php

@@ -0,0 +1,74 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Service;
+
+use App\Entity\Image;
+use App\Entity\SharedImage;
+use App\Entity\User;
+use App\Enum\TokenType;
+use Doctrine\ORM\EntityManagerInterface;
+use Symfony\Bridge\Twig\Mime\TemplatedEmail;
+use Symfony\Component\DependencyInjection\Attribute\Autowire;
+use Symfony\Component\Mailer\MailerInterface;
+
+class ShareService
+{
+    public function __construct(
+        private readonly EntityManagerInterface $em,
+        private readonly TokenService           $tokenService,
+        private readonly MailerInterface        $mailer,
+        #[Autowire('%env(int:SHARE_TOKEN_TTL_DAYS)%')]
+        private readonly int                    $tokenTtlDays,
+        #[Autowire('%env(MAILER_SENDER)%')]
+        private readonly string                 $mailerSender,
+    ) {}
+
+    public function share(Image $image, User $sharer, string $recipientEmail): SharedImage
+    {
+        $recipient = $this->em->getRepository(User::class)->findOneBy(['email' => $recipientEmail]);
+
+        if ($recipient === null) {
+            throw new \InvalidArgumentException('Recipient not found. They must have an account to receive shared photos.');
+        }
+
+        if ($recipient->getId() === $sharer->getId()) {
+            throw new \InvalidArgumentException('You cannot share a photo with yourself.');
+        }
+
+        // Idempotent: return existing pending share if one already exists
+        $existing = $this->em->getRepository(SharedImage::class)->findOneBy([
+            'sourceImage'   => $image,
+            'recipientUser' => $recipient,
+        ]);
+        if ($existing) {
+            return $existing;
+        }
+
+        $shared = new SharedImage($image, $recipient, $sharer);
+        $this->em->persist($shared);
+
+        $approveToken = $this->tokenService->issue(TokenType::ShareApprove, $image, $recipient, $recipientEmail, $this->tokenTtlDays);
+        $declineToken = $this->tokenService->issue(TokenType::ShareDecline, $image, $recipient, $recipientEmail, $this->tokenTtlDays);
+
+        $this->em->flush();
+
+        $email = (new TemplatedEmail())
+            ->from($this->mailerSender)
+            ->to($recipientEmail)
+            ->subject($sharer->getEmail() . ' shared a photo with you')
+            ->htmlTemplate('emails/share_notification.html.twig')
+            ->textTemplate('emails/share_notification.txt.twig')
+            ->context([
+                'sharer'       => $sharer,
+                'image'        => $image,
+                'approveToken' => $approveToken,
+                'declineToken' => $declineToken,
+            ]);
+
+        $this->mailer->send($email);
+
+        return $shared;
+    }
+}