[Build] Gitignore docker-compose.override.yml (per-developer dev override)

The override file exposes Kong on localhost:8000 for the Next.js dev
server and is auto-loaded by docker compose. Per Docker convention it
is per-developer state, not a shared/production artifact.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitignore

@@ -43,3 +43,6 @@ supabase/.temp/
 *.tsbuildinfo
 next-env.d.ts
 .claude/
+
+# docker
+docker-compose.override.yml