Cover cases where SQLPage functions span database and per-row
boundaries, including predicates, projections, and shared request/row
values.
Also add documentation to `QueryResult` and `BoundQuery`, tidy up
borrow expressions in the OIDC client, and rename a conflicting `rows`
alias in a test fixture.
SQLPage functions that are the whole value of a selected column now
execute after the database query, once per returned row. If the query
returns no rows, the function is not called. This ensures deterministic
behavior and prevents expensive or side-effectful operations from
running unnecessarily.
Ophir LOJKINE