fix: update render.py to support enhanced YAML structure

feat: enhance product YAMLs, upgrade models, add frontend with 4 LLM providers

feat: enhance digital_ad.j2 with production-quality Facebook ad framework

feat: implement deterministic pipeline with LLM-free evaluation (Phases 1-3)

feat: add full experimental matrix generator (2,025 runs)

feat: add prompt rendering system and product validation