BOT: Fix #769: Promote pairwise comparison test arguments to explicit parameters

[nikosbosse]

Summary

• Promotes test_type, one_sided, and n_permutations from ... passthrough to explicit named arguments in get_pairwise_comparisons(), pairwise_comparison_one_group(), and add_relative_skill()
• Improves API discoverability — users no longer need to read internal compare_forecasts() docs to discover these options
• Backward compatible: default values match the existing compare_forecasts() defaults (test_type = "non_parametric", one_sided = FALSE, n_permutations = 999)

Root cause

test_type, one_sided, and n_permutations were passed via ... through 3 levels of function calls (get_pairwise_comparisons → pairwise_comparison_one_group → compare_forecasts), making them invisible to users inspecting function signatures or autocomplete.

What changed

• R/pairwise-comparisons.R: Added test_type, one_sided, n_permutations as explicit parameters to get_pairwise_comparisons(), pairwise_comparison_one_group(), and add_relative_skill(). Removed ... from all three functions. Updated roxygen @param documentation.
• man/*.Rd: Regenerated documentation for the three affected functions.
• tests/testthat/test-pairwise_comparison.R: Added 7 new tests covering explicit argument acceptance, default values, backward compatibility, and argument threading through the call chain.

Test plan

• All 7 new tests pass (formals checks, explicit arg passing, default values, regression)
• Full test suite passes (713 tests, 0 failures)
• R CMD check: 0 errors, 0 warnings, 2 notes (pre-existing)

Closes #769

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.84%. Comparing base (ac0c01a) to head (cde71ce).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1090      +/-   ##
==========================================
+ Coverage   97.83%   97.84%   +0.01%     
==========================================
  Files          35       35              
  Lines        1845     1854       +9     
==========================================
+ Hits         1805     1814       +9     
  Misses         40       40              

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[nikosbosse]

CLAUDE: Clean, minimal refactor that correctly promotes test_type, one_sided, and n_permutations from ... to explicit named parameters across get_pairwise_comparisons(), pairwise_comparison_one_group(), and add_relative_skill(). Defaults match upstream compare_forecasts() exactly. NULL test_type for skipping p-values still works. All 7 new tests pass, no regressions in existing suite. Verdict: approve.

[nikosbosse]

@seabbs do you have thoughts on this? Basically, it moves

  test_type = c("non_parametric", "permutation"),
  one_sided = FALSE,
  n_permutations = 999

from ... to named parameters. I don't feel strongly...