fix(googlebooks): report more pages when limit is above the 40 result maximum

[splitsec2]

Kept small on purpose so it's easy to review. Same kind of small fix as #1429 to #1432, so see the question in #1429 about separate PRs versus combined. I'm sending them separately until I hear otherwise.

search_paginated guesses has_more as len(books) >= options.limit. Google Books returns at most 40 per page and search already caps maxResults at 40, but /api/metadata/search accepts a limit up to 100. With a limit over 40 a full page of 40 never reaches limit, so has_more is always False. The UI sends 40, so this only affects direct API callers.

The Google provider now overrides search_paginated to apply the same cap before the base heuristic runs. A full page of 40 with a limit of 100 reports more results and a short page doesn't. The first test fails on current main. Ruff, basedpyright and tests/metadata pass.

The one red check is the existing clock-dependent test test_a_queued_torrent_asks_for_a_grace_once, which fails on any runner that booted recently. It is fixed in #1426 and is not caused by this change.