fix(mailpit): bind UI to port 8025 so healthcheck passes; revert email FROM changes

Port 0 disabled the web UI but broke the built-in /readyz healthcheck.
Binding to 8025 keeps the UI accessible within the Docker network only
(no Traefik labels) and lets the container report healthy.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

gitea/.env.example

@@ -1,5 +1,5 @@
 TRAEFIK_HOST=dev.example.com
 NETWORK_NAME=falcon_network
 RUNNER_TOKEN=change_me
-EMAIL_FROM=hi@pivoine.art
+EMAIL_FROM=gitea@pivoine.art
 EMAIL_USER=Gitea