Fix Render seed import with persistent disk

[clank-tech]

Summary

• move Render/runtime SQLite storage to /app/storage so it does not shadow checked-in seed data
• copy the public ingredient seed to /app/seed/ingredients.json in the Docker image
• set INGREDIENTS_JSON for Render predeploy imports

Root cause

Render predeploy runs with the persistent disk mounted. Mounting storage at /app/data can hide the checked-in /app/data/ingredients.json file, causing npm run import-data to fail before startup.

Verification

• INGREDIENTS_JSON=data/ingredients.json SQLITE_PATH=/tmp/chekit-render-import-test-2/chekit.sqlite npm run import-data
• npm run smoke
• git diff --check

Note: local Docker build was not run because Docker is not installed on Clank's Mac yet.