fix: use separate port for integration tests to avoid conflicts

Integration tests now use port 8099 via docker-compose.test.yml with an
isolated project name, preventing conflicts with other services running
on port 8000.

docker-compose.test.yml

@@ -0,0 +1,10 @@
+services:
+  ffmpeg-worker:
+    build: .
+    ports:
+      - "8099:8000"
+    volumes:
+      - ./data:/data
+    environment:
+      - DATA_PATH=/data
+      - FFMPEG_TIMEOUT=3600