fix: write local instance config to settings.json from env vars

Adds LOCAL_OUTLINE_URL and LOCAL_OUTLINE_TOKEN to the generated
settings.json so the compare command can reach the outline-web container.

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

entrypoint.sh

@@ -8,6 +8,7 @@ cat > /work/settings.json <<EOF
 {
   "source": { "url": "${OUTLINE_URL}", "token": "${OUTLINE_TOKEN}" },
   "target": { "url": "${OUTLINE_URL}", "token": "${OUTLINE_TOKEN}" },
+  "local":  { "url": "${LOCAL_OUTLINE_URL:-}", "token": "${LOCAL_OUTLINE_TOKEN:-}" },
   "sync":   { "allow_deletions": false }
 }
 EOF