feat : error tracking backend vers GlitchTip (prod-only, inerte sans DSN)

Ajout du SDK sentry/sentry-symfony enregistré prod-only, config sentry.yaml
(DSN runtime, release app.version, 4xx ignorés, pas de tracing) et handler
Monolog ERROR+. Sans SENTRY_DSN le SDK est no-op. Transport réseau via
Tailscale (infra, hors repo).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

config/bundles.php

@@ -9,6 +9,7 @@ use Doctrine\Bundle\MigrationsBundle\DoctrineMigrationsBundle;
 use Lexik\Bundle\JWTAuthenticationBundle\LexikJWTAuthenticationBundle;
 use Nelmio\CorsBundle\NelmioCorsBundle;
 use Symfony\Bundle\FrameworkBundle\FrameworkBundle;
+use Sentry\SentryBundle\SentryBundle;
 use Symfony\Bundle\MonologBundle\MonologBundle;
 use Symfony\Bundle\SecurityBundle\SecurityBundle;
 use Symfony\Bundle\TwigBundle\TwigBundle;
@@ -24,4 +25,5 @@ return [
     LexikJWTAuthenticationBundle::class => ['all' => true],
     MonologBundle::class                => ['all' => true],
     DoctrineFixturesBundle::class       => ['dev' => true, 'test' => true],
+    SentryBundle::class                 => ['prod' => true],
 ];