v0.2.0 - Signal/statistics and RMHMC reliability fixes

This release focuses on analysis correctness, HMC diagnostics, and hot-path performance.

Highlights:

• Added jackknife uncertainty output for flux profiles in SU(2) scan output.
• Switched scan autocorrelation estimate to a Madras-Sokal self-consistent window.
• Logged per-trajectory RMHMC acceptance and cumulative acceptance rate (smeared and unsmeared).
• Guarded root path defaults and ensured checkpoint directory creation in RMHMC scripts.
• Replaced expensive complex power in SU(N) heatbath subgroup normalization with direct division.
• Added high-statistics postprocessing tool to the public snapshot (jackknife/covariance fit pipeline).