Replace requirements.txt with pipenv for consistent development environments. Pipenv maintains a superior Lockfile similar to NPM. Added additional development dependencies and mypy configuration.
This contains a package update too:
alembic from 1.12.1 to 1.13.2
flask from 3.0.0 to 3.0.3
SQLAlchemy from 2.0.23 to 2.0.31