Update LexiMind: improved training, model architecture, and evaluation

Full training run, code cleanup, mypy/ruff fixes

feat: Add FLAN-T5 compatibility with relative position bias

Build: Pin ruff to v0.4.4 in pre-commit to match CI

Chore: Update pre-commit hooks and fix formatting

Style: Fix formatting for models and tests

Refactor: Consolidate dependencies, improve testing, and add CI/CD

Implemented the following parts for the Transformer model: poisional_encoding, feedfoward, encoder, and skeleton of decoder. As well as Test cases for each class respectively and visualizations

Implemented ScaledDotProduct Attention and Multi-Head Attention