Add Key Takeaways card to left column (part 2)

Model insights card and heavy noble EN fidelity (part 2)

Refine fidelity scoring, UI panel, and add EN trend plot (part 2)

Layered Comparison Fidelity: core score, categories, proxy quality (part 2)

Allen EN validation, noble-gas fixes, observables UI polish (part 2)

Period-aware radius proxy, clickable trend plots, and period filter (part 2)

Add stability-based covalent radius proxy with fidelity weighting (part 2)

Add covalent atomic radius to observables validation table (part 2)

Period-relative IE comparison for comparison fidelity (part 2)

Phase 2: composite comparison fidelity, expanded μ data, electron affinity (part 2)

Refactor experimental comparison with compare_to_experiment() and validation table (part 2)

Add experimental magnetic moment validation to Observables panel (part 2)