[AZ-180] Refactor detection event handling and improve SSE support

- Updated the detection image endpoint to require a channel ID for event streaming.
- Introduced a new endpoint for streaming detection events, allowing clients to receive real-time updates.
- Enhanced the internal buffering mechanism for detection events to manage multiple channels.
- Refactored the inference module to support the new event handling structure.

Made-with: Cursor

tests/test_az178_streaming_video.py

@@ -419,7 +419,10 @@ class TestDetectVideoEndpoint:
             from fastapi.testclient import TestClient
             client = TestClient(main.app)
             token = _access_jwt()
-            with patch.object(main, "get_inference", return_value=_CaptureInf()):
+            with (
+                patch.object(main, "JWT_SECRET", _TEST_JWT_SECRET),
+                patch.object(main, "get_inference", return_value=_CaptureInf()),
+            ):
                 # Act
                 r = client.post(
                     "/detect/video",