Fix some :has() bugs.

[wRAR]

1. :has(> X) and :has(~ X) attach the inner condition to the wrong element
2. :has(+ X) drops the subselector's condition and never matches *
3. :not(:has(X)) translates to an always-true predicate — silently matches everything
4. -of-type pseudo-classes and :scope chained after :has() emit malformed XPath

Found and fixed by an LLM, all test cases validated manually.

This rewrites the original :has() implementation to use conditions which fixes bugs and is cleaner.

The unused join() args are removed directly per

cssselect/cssselect/xpath.py

Line 145 in 743c6e5

#### HERE BE DRAGONS

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.70%. Comparing base (743c6e5) to head (fba5de9).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #166      +/-   ##
==========================================
+ Coverage   96.61%   96.70%   +0.09%     
==========================================
  Files           3        3              
  Lines         885      881       -4     
  Branches      136      133       -3     
==========================================
- Hits          855      852       -3     
  Misses         14       14              
+ Partials       16       15       -1     

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