serve.sh: mkdir -p data before logging (fresh-checkout fix for new nodes)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

scripts/serve.sh

@@ -6,6 +6,7 @@
 # On first run the owner account + one-time password print to data/server.log.
 set -euo pipefail
 cd "$(dirname "$0")/.."
+mkdir -p data                         # gitignored — absent on a fresh checkout
 lsof -ti:8777 | xargs kill 2>/dev/null || true
 sleep 1
 nohup /opt/homebrew/bin/uv run uvicorn server.main:app --host 0.0.0.0 --port 8777 \