Implement memory-aware progressive fetching in BigQuery's fetch_data
method. Large result sets (950+ MB) previously crashed Chrome by loading
everything into memory at once. The fix samples an initial batch to
estimate row size, then fetches only as many rows as fit within the
BQ_FETCH_MAX_MB config limit (default 200 MB). A warning toast is shown
to users when results are truncated.
This is always-on with no feature flag -- operators control the budget
via the BQ_FETCH_MAX_MB config constant.
Originally by @ethan-l-geotab in apache#36387.
Co-authored-by: ethan-l-geotab <ethanliong@geotab.com>
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
