[Alexander-Mitrofanov]

Summary

• trace a representative minimum-free-energy interaction inside every finally selected model-P site while retaining the site ensemble energy as Eens for ranking and filtering
• expose Eens in CSV and text output, make model-P CSV output include and sort by it by default, and keep MFE structures and energy contributions in E
• update the browser controls, result sorting/deltas, parameter import, documentation, and regression coverage, including seeded and singleton explicit-seed cases

Validation

• release build: make tests -j2 — 11/11 passed
• debug build: make tests -j2 — 11/11 passed
• npm --prefix gui test — 32/32 passed
• python -m py_compile scripts/wasm/test-browser.py
• manual model-P CLI checks for unseeded, seeded, explicit-seed, singleton-seed, normal text, default CSV, and all-column CSV output

Compatibility

For model P, E and its component columns now describe the reported representative MFE structure. Eens retains the ensemble energy previously stored in E and remains the objective for output energy filters and ranking. Default model-P CSV gains the Eens column and is sorted by it.

Fixes #319