Add rate limiting on login, order, invitation, contact routes

- Login: 5 attempts / 15 min (Symfony login_throttling)
- Order create: 10 / 5 min (sliding window)
- Invitation respond/register: 5 / 15 min
- Contact form: 3 / 10 min
- RateLimiterSubscriber with route-to-limiter mapping
- Returns 429 when rate limited

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

composer.json

@@ -41,6 +41,7 @@
         "symfony/process": "8.0.*",
         "symfony/property-access": "8.0.*",
         "symfony/property-info": "8.0.*",
+        "symfony/rate-limiter": "8.0.*",
         "symfony/redis-messenger": "8.0.*",
         "symfony/runtime": "8.0.*",
         "symfony/security-bundle": "8.0.*",