feat(tflite): integrate medgemma_micro_cardio_350m model and M2 testing dashboard

Permanently ingest 1500 cardiac QA dataset into model weights, update disclaimer, add greeting intelligence, and recreate safetensors checkpoint

weights: update medgemma_micro_cardio_edge.safetensors with 4-bit Qwen2.5-0.5B and 1D-Conformer

feat: upgrade to sub-512MB mobile architecture for iOS (Core ML) and Android (LiteRT)

Initial commit: MedGemma-Micro multimodal cardiology edge model with lifestyle management & legal waiver guard