fix: remove deprecated edge methods from SimplicialComplex

[leotrs]

Summary

• Removed 5 deprecated methods from SimplicialComplex: add_edge, add_edges_from, add_weighted_edges_from, remove_edge, remove_edges_from
• These methods previously issued a UserWarning and silently delegated to the simplex equivalents (add_simplex, add_simplices_from, etc.)
• They now raise XGIError with a message pointing to the correct method

Since SimplicialComplex inherits from Hypergraph, these methods must be explicitly overridden — otherwise the parent's add_edge would be exposed, which would add edges without simplicial closure.

Note: read_json/write_json deprecation is tracked separately in #697.

Test plan

• All 392 tests pass
• Doctests pass
• No tests or internal code used the deprecated methods on SimplicialComplex

🤖 Generated with Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 54.54545% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.77%. Comparing base (6e7fe50) to head (672dd76).
⚠️ Report is 23 commits behind head on dev.

Files with missing lines	Patch %	Lines
xgi/core/simplicialcomplex.py	50.00%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev     #696      +/-   ##
==========================================
+ Coverage   93.59%   93.77%   +0.18%     
==========================================
  Files          66       66              
  Lines        5120     5112       -8     
==========================================
+ Hits         4792     4794       +2     
+ Misses        328      318      -10     

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