feat: complete Gradio app and Docker deployment (Task 3.2 & 3.3)

fix: resolve all 468 ruff linting errors (code quality enforcement complete)

refactor: implement comprehensive workflow improvements and process documentation

feat: implement comprehensive MLflow tracking with MLOps best practices

feat: add full training script with visualization

feat: add training pipeline with checkpointing

feat: add CNN model architectures

feat: add data augmentation with visualization notebook

feat: add preprocessing pipeline with PyTorch Dataset

feat: add data quality analysis module

feat: extract MnistDataloader to reusable module

feat: complete Phase 0 - project setup