refactor(gitea): move VPS IPv4 address to .env as VPS_IPV4

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

gitea/compose.yml

@@ -37,7 +37,7 @@ services:
       GITEA__ui__DEFAULT_THEME: nord
       GITEA__ui__ENABLE_FEED: "true"
     ports:
-      - "82.165.139.220:22:2222"
+      - "${VPS_IPV4}:22:2222"
     volumes:
       - ../.data/gitea/data:/data
       - ../.data/gitea/config:/etc/gitea