Add comprehensive test suite for image processing and related services

- Implement tests for database generator to ensure proper session handling.
- Create tests for EXIF extraction and conversion functions.
- Add tests for image-related endpoints, ensuring proper data retrieval and isolation between clients.
- Develop tests for OCR functionality, including language detection and text extraction.
- Introduce tests for the image processing pipeline, covering success and failure scenarios.
- Validate rate limiting functionality and ensure independent counters for different clients.
- Implement scraper tests to verify HTML content fetching and error handling.
- Add unit tests for various services, including storage and filename generation.
- Establish worker entry point for ARQ to handle background image processing tasks.

app/workers/redis_client.py

@@ -0,0 +1,28 @@
+"""
+Client Redis partagé — pool de connexions async pour ARQ et Pub/Sub.
+"""
+from redis.asyncio import ConnectionPool, Redis
+
+from app.config import settings
+
+_pool: ConnectionPool | None = None
+
+
+async def get_redis_pool() -> Redis:
+    """Retourne un client Redis avec pool de connexions partagé."""
+    global _pool
+    if _pool is None:
+        _pool = ConnectionPool.from_url(
+            settings.REDIS_URL,
+            max_connections=20,
+            decode_responses=True,
+        )
+    return Redis(connection_pool=_pool)
+
+
+async def close_redis_pool() -> None:
+    """Ferme proprement le pool de connexions Redis."""
+    global _pool
+    if _pool is not None:
+        await _pool.disconnect()
+        _pool = None