Evaluate empirical and block-bootstrap scenario baseline

[Tim55667757]

Parent Feature: #43
Parent roadmap: #28

Scope

Evaluate a simple empirical/bootstrap family as a candidate data-driven scenario model before introducing heavier parametric models.

Acceptance criteria

• concrete R&D use case is stated;
• block length/sampling semantics are explicit;
• reproducibility is supported;
• comparison against legacy_v1 uses M2 metrics;
• strengths/limitations are documented before adoption.