Add comprehensive short100 Jacobian report

[charlesmartin14]

Summary

• persist every compact Jacobian spectral observation with amplitude, Gram eigenvalue, observation unit, and represented multiplicity
• add a report builder joining reduced Jacobian results to WeightWatcher raw/clip_xmax controls and train/test performance
• generate combined MuonClip-RMS versus AdamW alpha, fit-quality, tail-support, performance, correlation, and spectral-evolution figures
• write six analysis-ready CSV tables, a manifest, and a browsable HTML index
• force an automatic compact backfill when an older completed reduced run lacks spectral data

Validation

• Python compilation and shell syntax checks passed
• full synthetic end-to-end report run passed
• generated 12 figures, six CSV tables, a manifest, and an HTML index
• visually inspected the combined alpha comparison and corrected shared legend placement
• git diff --check passed

The sandbox lacks PyTorch/pytest, so the new repository tests were exercised as direct import/helper checks rather than through pytest.