Fix any()/all() reductions with masked subsets and scalar semantics

[t-kalinowski]

• Implement any()/all() lowering for logical reductions, including mask-hoisting.
• Fix scalar masked subset semantics (empty selection yields FALSE for any(), TRUE for all()).
• Handle 1-element array constructors (e.g. c(FALSE) -> [ .false. ]) so reductions stay scalar.
• Avoid pack() temporaries for masked reductions by rewriting:
  • any(x[mask]) -> any(x .and. mask)
  • all(x[mask]) -> all((.not. mask) .or. x)
• Fix scalar+hoisted-mask merge() so it never emits rank-1 RHS when x is a 1-element array constructor.

Tests:

• Added regression coverage in tests/testthat/test-subset-reduction.R
• Ran: R -q -e "devtools::test()"

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[chatgpt-codex-connector]

Treat length-1 mask constructors as scalars in reductions

When a logical mask like c(TRUE) is used in subsetting (e.g., any(x[c(TRUE)]) with x a length>1 vector), [ hoists the mask as a rank-1 array constructor. This branch then emits any((x) .and. ([.true.])) or all((.not. ([.true.])) .or. (x)). In Fortran, a length-1 array constructor is not conformable with a length-N array, so the .and./.or. operations are invalid and the generated code will fail to compile. The mask needs to be treated as a scalar in this case (e.g., by reducing it with any() or special-casing length-1 constructors) to match R’s recycling semantics.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.78%. Comparing base (3ef7c49) to head (1d1340e).
⚠️ Report is 22 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #92      +/-   ##
==========================================
+ Coverage   92.76%   92.78%   +0.01%     
==========================================
  Files          27       27              
  Lines        5734     5749      +15     
==========================================
+ Hits         5319     5334      +15     
  Misses        415      415              

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