fix: Keep pagination iterators advancing past fully-filtered pages

[vdusek]

The offset- and cursor-based pagination iterators stopped as soon as a page's items list came back empty. But under dataset filters (clean, skip_empty, skip_hidden), the API can scan a full chunk (up to 1000 items) while returning none — items=[] with x-apify-pagination-count: 1000. The iterators broke on that page and silently never yielded any item behind it, even though the offset bookkeeping (max(count, len(items))) had already advanced past the scanned rows.

Now all four iterators (offset + cursor, sync + async) terminate on the number of items scanned rather than returned: they keep advancing the offset/cursor across fully-filtered pages and stop only when a page scans nothing. The limit and cursor is None checks are unchanged. Behavior is identical for every response without a divergent count (collection endpoints, ListOfRequests).

Added a regression test for each of the four iterators.

Related to https://github.com/apify/apify-core/issues/27324.

✍️ Drafted by Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.62%. Comparing base (c1bffc6) to head (90ad295).
⚠️ Report is 8 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #964      +/-   ##
==========================================
- Coverage   94.64%   94.62%   -0.02%     
==========================================
  Files          58       58              
  Lines        5263     5246      -17     
==========================================
- Hits         4981     4964      -17     
  Misses        282      282              

Flag	Coverage Δ
integration	92.26% <100.00%> (-0.05%)	⬇️
unit	83.89% <100.00%> (-0.06%)	⬇️

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[Pijukatel]

Can you please check the JS implementation as well