Add bipermutedimsopadd! overloads

[mtfishman]

Summary

Companion PR to ITensor/TensorAlgebra.jl#158.

• Add bipermutedimsopadd! overloads for AbstractSectorArray and AbstractGradedArray as the primary permutation implementation (with fermion phase, block iteration)
• Existing permutedimsopadd! overloads removed (TensorAlgebra's default flat→biperm forwarding handles them)
• Qualify existing check_input definitions as TensorAlgebra.check_input overloads
• Call check_input(bipermutedimsopadd!, ...) for generic axes validation in both overloads
• Use [sources] to resolve TensorAlgebra from the mf/contractopadd branch (remove before merge, bump compat to 0.9)
• Bump version to v0.8.4

Breaking changes

None for downstream consumers. This adapts GradedArrays to TensorAlgebra's new bipermutedimsopadd! primitive.

Test plan

• All existing tests pass (tensoralgebra, full runtests.jl)
• Tested against TensorAlgebra.jl mf/contractopadd branch

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.18%. Comparing base (d470cf8) to head (2a4367a).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #152      +/-   ##
==========================================
- Coverage   87.33%   87.18%   -0.15%     
==========================================
  Files          20       20              
  Lines        1263     1264       +1     
==========================================
- Hits         1103     1102       -1     
- Misses        160      162       +2     

Flag	Coverage Δ
docs	0.00% <0.00%> (ø)

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