Add Art section: upload named images, gallery, delete

- Artwork entity (name, stored filename, original name, mime, size, date)
- /art gallery grid; /art/upload (name + image file, PNG/JPEG/GIF/WebP,
  20M cap); /art/{id}/file streams the image behind auth; /art/{id}/delete
  (CSRF) removes row + file
- files stored under var/uploads/art/ (git-ignored, on the php_var volume
  in Docker), served through a controller so they stay login-gated
- "Art" nav item

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

src/Entity/Artwork.php

@@ -0,0 +1,113 @@
+<?php
+
+namespace App\Entity;
+
+use App\Repository\ArtworkRepository;
+use Doctrine\DBAL\Types\Types;
+use Doctrine\ORM\Mapping as ORM;
+use Symfony\Component\Validator\Constraints as Assert;
+
+#[ORM\Entity(repositoryClass: ArtworkRepository::class)]
+#[ORM\Table(name: 'artwork')]
+class Artwork
+{
+    #[ORM\Id]
+    #[ORM\GeneratedValue]
+    #[ORM\Column]
+    private ?int $id = null;
+
+    #[ORM\Column(length: 200)]
+    #[Assert\NotBlank]
+    private string $name = '';
+
+    /** Randomised on-disk name under var/uploads/art/. */
+    #[ORM\Column(length: 120)]
+    private string $filename = '';
+
+    #[ORM\Column(length: 255, nullable: true)]
+    private ?string $originalName = null;
+
+    #[ORM\Column(length: 100)]
+    private string $mimeType = 'application/octet-stream';
+
+    #[ORM\Column(type: Types::INTEGER)]
+    private int $size = 0;
+
+    #[ORM\Column(type: Types::DATETIME_IMMUTABLE)]
+    private \DateTimeImmutable $uploadedAt;
+
+    public function __construct()
+    {
+        $this->uploadedAt = new \DateTimeImmutable();
+    }
+
+    public function getId(): ?int
+    {
+        return $this->id;
+    }
+
+    public function getName(): string
+    {
+        return $this->name;
+    }
+
+    public function setName(string $name): static
+    {
+        $this->name = $name;
+
+        return $this;
+    }
+
+    public function getFilename(): string
+    {
+        return $this->filename;
+    }
+
+    public function setFilename(string $filename): static
+    {
+        $this->filename = $filename;
+
+        return $this;
+    }
+
+    public function getOriginalName(): ?string
+    {
+        return $this->originalName;
+    }
+
+    public function setOriginalName(?string $originalName): static
+    {
+        $this->originalName = $originalName;
+
+        return $this;
+    }
+
+    public function getMimeType(): string
+    {
+        return $this->mimeType;
+    }
+
+    public function setMimeType(string $mimeType): static
+    {
+        $this->mimeType = $mimeType;
+
+        return $this;
+    }
+
+    public function getSize(): int
+    {
+        return $this->size;
+    }
+
+    public function setSize(int $size): static
+    {
+        $this->size = $size;
+
+        return $this;
+    }
+
+    public function getUploadedAt(): \DateTimeImmutable
+    {
+        return $this->uploadedAt;
+    }
+}