Consolidate production code and separate research artifacts

[astrojaket]

What changed

• import the reusable cloudy SH4 and exact correlated-k performance work
• keep personal MPI, species-scaling, and WASP-69 benchmark changes out of the production import
• move the exploratory L 98-59 b study, its study-only helper, configuration, tests, and reports off production main
• remove Taylor 2021 paper-specific inputs, figures, benchmark, and test
• remove the target-specific WASP-69 sampler comparison tool and test
• replace personal absolute executable and result paths with explicit CLI arguments, environment variables, or portable relative paths

Branch separation

• the L 98-59 b study is preserved on codex/research-l98-59b-flat-clr
• JAX/Metal, Solar System, emission-intercomparison, Stage 9, PICASO rebinning, and HAT-P-32b work remain on separate local or remote branches
• pressure-quench/stellar-contamination and NEMESIS vertical-profile work remain unmerged until they are rebased and split cleanly

Validation

• 496 passed, 1 skipped in the robert-exoplanets Conda environment with JAX forced to CPU for the normal suite
• ruff check . passed
• sdist and wheel built successfully
• git diff --check passed
• no /Users/... or Dropbox paths remain outside historical review documents