feat: production deployment - full update with providers, admin, glossaries, pricing, tests

Major changes across backend, frontend, infrastructure:
- Provider system with model selection (Google, DeepL, OpenAI, Ollama, Google Cloud)
- Admin panel: user management, pricing, settings
- Glossary system with CSV import/export
- Subscription and tier quota management
- Security hardening (rate limiting, API key auth, path traversal fixes)
- Docker compose for dev, prod, and IONOS deployment
- Alembic migrations for new tables
- Frontend: dashboard, pricing page, landing page, i18n (en/fr)
- Test suite and verification scripts

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

middleware/tier_quota.py

@@ -53,30 +53,15 @@ class QuotaResult:
 
 
 # ---------------------------------------------------------------------------
-# Redis backend
+# Redis backend (shared client from core.redis)
 # ---------------------------------------------------------------------------
 
-_async_redis = None
-
 
 def _get_async_redis():
-    """Return async Redis client or None. Uses REDIS_URL from env. Single shared client."""
-    global _async_redis
-    if _async_redis is not None:
-        return _async_redis if _async_redis is not False else None
-    url = os.getenv("REDIS_URL", "").strip()
-    if not url:
-        _async_redis = False
-        return None
-    try:
-        import redis.asyncio as redis
-        _async_redis = redis.Redis.from_url(url, decode_responses=True)
-        logger.info("Tier quota: using Redis for daily quota")
-        return _async_redis
-    except Exception as e:
-        logger.warning("Tier quota: Redis unavailable (%s), using in-memory fallback", e)
-        _async_redis = False
-        return None
+    """Return async Redis client or None. Uses shared client from core.redis."""
+    from core.redis import get_async_redis
+
+    return get_async_redis()
 
 
 # ---------------------------------------------------------------------------