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.

worker.py

@@ -0,0 +1,14 @@
+"""
+Entrypoint du worker ARQ — traitement des images en arrière-plan.
+
+Lancer avec : python worker.py
+
+Le worker écoute les queues Redis 'standard' et 'premium' et traite
+les tâches de pipeline image (EXIF → OCR → AI).
+"""
+import asyncio
+from arq import run_worker
+from app.workers.image_worker import WorkerSettings
+
+if __name__ == "__main__":
+    asyncio.run(run_worker(WorkerSettings))