Remove redundant feasibility checks from hot prediction paths

[Alexander-Mitrofanov]

Implements AP-1, the first measured phase-3 optimization from discussion #232, on the current C++23 base.

areComplementary() already enforces nucleotide complementarity and both accessibility predicates. This change removes duplicate direct accessibility checks from hot predictor and seed paths while preserving the existing row-level screens, recurrence traversal, arithmetic, candidate ordering, and accepted base pairs. A focused counting regression proves the default no-bulge seed path no longer repeats those calls.

The originally reviewed source/test change remains byte-identical to commit 56ac5eb. Commit fd55acb integrates the current C++23 base without conflicts, and 0a5cb8a adds the ChangeLog entry requested in review.

Validation

• scientific parent: 902236560b48e0aa27166b0be42a0bea8e262442
• candidate head: 0a5cb8a0aade74d18e901f3b0f48cf1627800f76
• executable optimization source: fd55acb
• pinned GCC 14.4.0 / Boost 1.85.0 / ViennaRNA 2.7.2 environment
• clean configure/build and complete IntaRNA tests pass for both immutable references
• both AP-1 cases have identical raw and canonical output hashes
• LP workload: 3.493944 +/- 0.015863 s to 3.454898 +/- 0.014861 s (1.011x)
• noLP workload: 0.750087 +/- 0.011438 s to 0.692586 +/- 0.003439 s (1.083x)
• mean peak RSS remains within measurement noise

Batch ap1-current-cpp23-base-20260826 uses parent/candidate benchmark IDs c3a4d4509048019964d420c732cfecf116597eaa1d6944a8db83c3a9e0074e44 and 119aaba30a7e6b51d46f2f4b982bc3de1a1c728cf87a689058a8562f3f7120df.

The schema-validated JSON, compressed outputs, and generated report are in benchmark evidence commit 392147c and benchmark PR #3. The older 8bd1676 -> 56ac5eb measurements remain historical evidence and are superseded for acceptance by this current-base batch.

The refreshed C/C++ CI run is green on the exact candidate head: GCC 14 release, GCC 14 debug, and Apple Clang/libc++ release each pass build, install, the complete test suite, independent compilation of every installed public header, and an installed pkg-config consumer. The benchmark repository's validation run is also green.

[martin-raden]

I have checked and approved all changes.

• TODO: update "Changelog" file accordingly

and this will be ready to merge