fix: Normalize query params in dataset create_items_public_url

[vdusek]

DatasetClient.create_items_public_url (and its async twin) passed _build_params output straight to urlencode, bypassing the _parse_params normalization that the real HTTP request path applies. As a result, boolean and list query params ended up as Python reprs in the signed URL — e.g. create_items_public_url(clean=True, fields=['title', 'url']) produced clean=True&fields=%5B%27title%27%2C+%27url%27%5D instead of clean=true&fields=title,url. Consumers of the shared URL then got unclean/unfiltered items or an API error.

The fix routes the params through self._http_client._parse_params(...) before urlencode, so the public URL matches exactly what an actual API request would send (bool→true/false, list→comma-joined, None dropped). Added regression tests for both the sync and async clients.

✍️ 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 (4439d11).
⚠️ Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #963      +/-   ##
==========================================
- Coverage   94.64%   94.62%   -0.02%     
==========================================
  Files          58       58              
  Lines        5263     5244      -19     
==========================================
- Hits         4981     4962      -19     
  Misses        282      282              

Flag	Coverage Δ
integration	92.42% <100.00%> (+0.12%)	⬆️
unit	83.88% <100.00%> (-0.06%)	⬇️

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[vdusek]

It's discutable whether http_client._parse_params should remain private. This is its only use case so far, so I'd probably keep it private as it is, but I'm open to discussing it.

[Pijukatel]

Isn't this just a refactoring? Extracting code used in 6 places into one function. All the new and previous tests are passing even when reverting the code changes in src.

[Pijukatel]

Ok, I mssed some tests

[vdusek]

Ok, I mssed some tests

Also, the PR description mentions it.