Add background task to export suspicious IPs to text file

- Implement export-malicious-ips task that queries distinct IPs flagged
    as is_suspicious from database and writes to exports/malicious_ips.txt
  - Add exports volume mount to docker-compose.yaml for host persistence
  - Update entrypoint.sh to fix ownership of exports directory for krawl user
  - Update Dockerfile to create /app/exports directory during build

Other tasks can be added by creating them in the tasks dir using the same setup as this task.
All tasks *MUST* include a TASK_CONFIG dict and a main method in the file to work correctly.

entrypoint.sh

@@ -2,7 +2,7 @@
 set -e
 
 # Fix ownership of mounted directories
-chown -R krawl:krawl /app/logs /app/data 2>/dev/null || true
+chown -R krawl:krawl /app/logs /app/data /app/exports 2>/dev/null || true
 
 # Drop to krawl user and run the application
 exec gosu krawl "$@"