26.03.02 — External mesh input and EOS safety

First release under calendar versioning. Adds support for externally defined radial meshes, enabling coupling with the Zalmoxis structure solver for super-Earth interiors where the analytical Adams-Williamson density profile breaks down.

External mesh input

SPIDER can now read radial mesh files (radius, pressure, density, gravity) produced by an external structure solver instead of computing its own Adams-Williamson mesh. This is the SPIDER-side requirement for coupling with Zalmoxis in PROTEUS.

• New options: -MESH_SOURCE 1 -mesh_external_filename <path>
• File format: header line with node counts, then surface-to-CMB rows of r P rho g in SI
  units (gravity negative)
• Input validation: rejects invalid MESH_SOURCE values, requires filename when
  MESH_SOURCE=1, warns if file geometry mismatches -radius or -coresize by more than 1%

EOS out-of-range safety

• Thermal expansion coefficient (alpha) clamped to zero when negative, preventing NaN
  propagation through mixing-length theory at phase-transition boundaries
• First-occurrence warnings when pressure or entropy fall outside EOS lookup table bounds
• Compile-time guard against quad-precision PETSc builds (__float128), where
  fscanf("%lf") would silently corrupt PetscScalar values

Other

• Switched to calendar versioning (calver)
• Documentation updates by @stuitje

What's Changed

• Sync changes from custom OSF spider by @nichollsh in
  #1
• Documentation for SPIDER by @stuitje in #2
• Documentation update by @stuitje in #4
• Add external mesh input and EOS out-of-range safety by @timlichtenberg in #5

New Contributors

• @nichollsh made their first contribution in #1
• @stuitje made their first contribution in #2
• @timlichtenberg made their first contribution in #5

Full Changelog: 0.2.0...26.03.02