docs: add Quickstart with config-selection guidance for all 5 configs

Document selector_v3_windows/selector_v3_policy_vectors configs; update provenance and checksums (incl. missing selector_v2_registry.parquet checksum)

Add selector_v3_policy_vectors config (multi-domain causal-robustness policy outcomes)

Add selector_v3_windows config (multi-domain causal-robustness window features)

Add selector-v2 registry training data

Add selector-v2 registry training data

Add selector-v2 registry training data

Publish selector regret and policy suitability benchmark

initial commit