Change default HOST_PORT to 5057 — 5056 is actually taken by arr-summary

arr-summary's own docs say 5055, but it's really deployed on 5056
(confirmed via docker ps on the Unraid box), which collided with
massprice's original default.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01H6TgffxTvYhqxykAbVQg2v

docker-compose.yml

@@ -6,7 +6,7 @@ services:
     # and causes renderer crashes — this is the standard mitigation.
     shm_size: "1gb"
     ports:
-      - "${HOST_PORT:-5056}:5000"
+      - "${HOST_PORT:-5057}:5000"
     volumes:
       # Schedules, run history, the rule-name cache, and the saved
       # MassPrice login session must outlive `up -d --build`, which