feat: replace notifications with import status in profile dropdown

Remove the notification system entirely and show import progress
directly in the user dropdown menu. Block new imports while one
is already running.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/Entity/Notification.php

@@ -1,78 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace App\Entity;
-
-use App\Repository\NotificationRepository;
-use Doctrine\ORM\Mapping as ORM;
-
-#[ORM\Entity(repositoryClass: NotificationRepository::class)]
-class Notification
-{
-    #[ORM\Id]
-    #[ORM\GeneratedValue]
-    #[ORM\Column]
-    private ?int $id = null;
-
-    #[ORM\ManyToOne(targetEntity: User::class)]
-    #[ORM\JoinColumn(nullable: false)]
-    private ?User $user = null;
-
-    #[ORM\Column(length: 255)]
-    private ?string $message = null;
-
-    #[ORM\Column(name: 'is_read')]
-    private bool $read = false;
-
-    #[ORM\Column]
-    private \DateTimeImmutable $createdAt;
-
-    public function __construct()
-    {
-        $this->createdAt = new \DateTimeImmutable();
-    }
-
-    public function getId(): ?int
-    {
-        return $this->id;
-    }
-
-    public function getUser(): ?User
-    {
-        return $this->user;
-    }
-
-    public function setUser(?User $user): static
-    {
-        $this->user = $user;
-        return $this;
-    }
-
-    public function getMessage(): ?string
-    {
-        return $this->message;
-    }
-
-    public function setMessage(string $message): static
-    {
-        $this->message = $message;
-        return $this;
-    }
-
-    public function isRead(): bool
-    {
-        return $this->read;
-    }
-
-    public function setRead(bool $read): static
-    {
-        $this->read = $read;
-        return $this;
-    }
-
-    public function getCreatedAt(): \DateTimeImmutable
-    {
-        return $this->createdAt;
-    }
-}