fix: seed app.ini into writable config volume for Gitea 1.24+

Gitea 1.24+ persists settings back to app.ini on boot (e.g. WORK_PATH).
Mounting app.ini directly as a read-only swarm config makes that write
fail (logged error, possible repo-access bugs). Mount the rendered config
as app.ini.init and seed a writable copy in the config volume instead.

compose.yml

@@ -6,7 +6,7 @@ services:
     image: "gitea/gitea:1.27.1-rootless"
     configs:
       - source: app_ini
-        target: /etc/gitea/app.ini
+        target: /etc/gitea/app.ini.init
       - source: docker_setup_sh
         target: /usr/local/bin/docker-setup.sh
         mode: 0555