Landed via reviewed rebase onto main.

• Gate: go test ./internal/cmd -run 'TestGmailFilters(Create_Validation|Create_Forward_NoInputRequiresForce|TextPaths|List_NoFilters|Export)' -count=1, make lint, make test, make ci\n- Land commit: 93faf8f\n- Merge commit: fbb230b\n\nNarrowed the PR to the safe fit on current main: landed gmail filters export only. I left sync out because the current design is destructive-first (delete everything, then best-effort recreate) and still needs a dry-run / transactional / confirmation story before it’s mergeable.\n\nThanks @Jeswang!