fix: persist uploads across container rebuilds with Docker volume (AIIA-74)

Uploaded documents were lost on every redeploy because /app/uploads
had no persistent volume. Add uploads_data volume to docker-compose.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

docker-compose.yml

@@ -16,6 +16,8 @@ services:
       - ANTHROPIC_API_KEY=${ANTHROPIC_API_KEY}
       - OPENAI_API_KEY=${OPENAI_API_KEY}
       - ENCRYPTION_KEY=${ENCRYPTION_KEY}
+    volumes:
+      - uploads_data:/app/uploads
     depends_on:
       postgres:
         condition: service_healthy
@@ -51,3 +53,4 @@ services:
 volumes:
   postgres_data:
   meilisearch_data:
+  uploads_data: