feat: add CLAHE, label smoothing, TTA, and ensemble inference

fix(types): resolve all 8 mypy errors across 5 files

v2: SE attention, AMP, grad accumulation, rich model cards with Mermaid

Fix doubled images/images/ path in trainer dataset construction

Fix CI, unblock Kaggle training dispatch, upgrade demo app for HF Spaces

Enforce cloud-only compute policy, populate HF dataset, Colab notebooks

Initial project scaffold: CheXVision — Chest X-Ray Pathology Detection