fix: Remove Gitea env var pre-config (let wizard handle it)

The GITEA__* environment variables were conflicting with the
wizard-generated app.ini, causing crash loop on startup.

Simplified to only USER_UID/GID - let the wizard configure
everything else cleanly.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

infra/docker-compose.yml

@@ -15,11 +15,6 @@ services:
     environment:
       - USER_UID=1000
       - USER_GID=1000
-      - GITEA__database__DB_TYPE=sqlite3
-      - GITEA__server__DOMAIN=git.corrosionmgmt.com
-      - GITEA__server__SSH_DOMAIN=git.corrosionmgmt.com
-      - GITEA__server__ROOT_URL=https://git.corrosionmgmt.com/
-      - GITEA__security__INSTALL_LOCK=false # Allow initial setup wizard
     restart: always
     volumes:
       - ./gitea:/data