Data App refresh: force-fresh results with bypassCache

The data app refresh endpoint now accepts an optional bypassCache flag so an
explicit "refresh now" returns freshly-executed query results instead of the
cached tile result.

What's New

• New body field: POST /api/v1/accounts/{accountId}/data-products/{dataProductId}/data-apps/{dataAppId}/refresh
  accepts bypassCache: boolean (optional).
• Force-fresh execution: when true, every tile query is re-run against the
  warehouse and the result cache is refreshed. Powers the live auto-refresh
  control on dashboards, where short intervals (30s / 1m) need to reflect real
  data rather than a cached value.

Example Request

curl -X POST \
 https://tenant.bobsled.ai/api/v1/accounts/{accountId}/data-products/{dataProductId}/data-apps/{dataAppId}/refresh \
 -H "Authorization: Bearer YOUR_TOKEN" \
 -H "Content-Type: application/json" \
 -d '{ "bypassCache": true }'

Migration Notes

No changes required for existing integrations. When omitted, refresh behaves
exactly as before and continues to serve cached tile results within the cache
window.