A public generic interface whose specifics are private leaves nothing to gate

[chenyueqi]

tridiag_lu_solver and penta_lu_solver in CLUBB_core export only a generic (public :: tridiag_lu_solve; interface tridiag_lu_solve over three private specifics). f2py-golden-flat reports no subprogram the flat wrapper can spell; with an empty reason list because it only considers public subprograms and the specifics are private. The specifics of a public generic are reachable through the generic and should be gate-visible (either the frontend marks them public-via-generic, or the oracle and the gate resolve the generic to its specifics).

Found 2026-09-03 running the recast-clubb extension's tier-0 units (CLUBB_core of larson-group/clubb_release at 8ab3902, double precision, statistics off).

[chenyueqi]

Fixed on branch tier0-gaps (PR #25): a specific of a public generic is public through it (public_via), and the flat oracle calls through the generic. Labelled fixed-in-pr until the merge.