Remove the rows client-side fallback

## Goal

The rows hook still has a client-mode path that loads every row at once. That path only existed because the server could not always satisfy the view request. Once the server can handle those requests, the fallback should go away.

## Scope

* Remove the `client` branch in `buildQueryPlan`.
* Remove `CLIENT_PER_PAGE` and `CLIENT_PAGE_FETCH_CONCURRENCY` from `useCollectionRows.js`.
* Add a regression test that fails if the client-mode path comes back.

## Depends on

* #102
* #125
* #132
* #133

## Acceptance criteria

* The rows hook only has the server-mode path.
* No view falls back to client mode.
* A regression test covers the removal.

Start by reading buildQueryPlan and useCollectionRows.js to trace the client-mode path and the constants used by it. Add the requested regression test for the removal, then verify that the rows hook has only the server-mode path and no view falls back to client mode.

Written by the indexing model from the issue text.