Refactor project structure and enhance Docker configuration

- Updated `.dockerignore` to exclude test and development artifacts, optimizing the Docker image size.
- Refactored `main.py` to delegate execution to `duty_teller.run.main()`, simplifying the entry point.
- Introduced a new `duty_teller` package to encapsulate core functionality, improving modularity and organization.
- Enhanced `pyproject.toml` to define a script for running the application, streamlining the execution process.
- Updated README documentation to reflect changes in project structure and usage instructions.
- Improved Alembic environment configuration to utilize the new package structure for database migrations.

.dockerignore

@@ -10,3 +10,9 @@ __pycache__/
 *.plan.md
 data/
 .curosr/
+# Tests and dev artifacts (not needed in image)
+tests/
+.pytest_cache/
+conftest.py
+*.cover
+htmlcov/