fix(instance-ai): Pass user and sharingOptions to execution query

The execution adapter was passing `accessibleWorkflowIds` to
`findManyByRangeQuery`, but that field is not part of
`ExecutionSummaries.RangeQuery`. Without `user`/`sharingOptions`, the
query builder fell into `WHERE 1 = 0`, returning zero results every
time — causing the agent to loop on "Checking executions" without
finding anything.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>