v0.6.0: Population-sample calibration and cross-scenario targets

Features

• Population-sample calibration — population-sample primitives (copula / mixture / empirical), declared population sample + population_spread opt-in gate, LogNormal.from_median_iqr_width, deterministic-tiling up-sampling with exchangeable-row shuffle (#48)
• Cross-scenario targets — single self-contained pintless cross-input kind (#47)
• capture_bootstrap_samples util (#46)

Fixes

• Family-name extraction for multi-word surnames (tussenvoegsel) (#45)
• Read Zotero DB with immutable=1 to bypass Zotero 7+ lock (#44)

Note: population_spread introduces a new opt-in calibration contract — hence the minor bump.

Full changelog: v0.5.0...v0.6.0