feat: final smoke-test fixes + spectacular README + UI bugfixes

Overhaul: Plackett-Luce ranking, PII anonymization, live fairness dashboard + LLM-free fallback agents

feat: Phase 15 documentation + Phase 14 test fixes

feat: Phase 8 rationale generation — LLM + template fallback, validator

chore: create directory structure with __init__.py files and placeholder scripts