feat : MCP server infrastructure setup

Install symfony/mcp-bundle, add STDIO + HTTP transport config,
API token auth on User entity with custom authenticator and firewall,
generate-api-token console command, Nginx /_mcp location, fixture token.

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

src/Entity/User.php

@@ -67,6 +67,9 @@ class User implements UserInterface, PasswordAuthenticatedUserInterface
     #[ORM\Column(type: Types::DATETIME_IMMUTABLE)]
     private ?DateTimeImmutable $createdAt = null;
 
+    #[ORM\Column(length: 64, unique: true, nullable: true)]
+    private ?string $apiToken = null;
+
     #[ORM\ManyToOne(targetEntity: Client::class)]
     #[ORM\JoinColumn(nullable: true, onDelete: 'SET NULL')]
     #[Groups(['me:read', 'user:list', 'user:write'])]
@@ -184,5 +187,17 @@ class User implements UserInterface, PasswordAuthenticatedUserInterface
         return $this;
     }
 
+    public function getApiToken(): ?string
+    {
+        return $this->apiToken;
+    }
+
+    public function setApiToken(?string $apiToken): static
+    {
+        $this->apiToken = $apiToken;
+
+        return $this;
+    }
+
     public function eraseCredentials(): void {}
 }