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.

alembic/env.py

@@ -1,4 +1,4 @@
-"""Alembic env: use config DATABASE_URL and db.models.Base."""
+"""Alembic env: use duty_teller config DATABASE_URL and db.models.Base."""
 
 import os
 import sys
@@ -9,8 +9,8 @@ from alembic import context
 
 sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
 
-import config
-from db.models import Base
+import duty_teller.config as config
+from duty_teller.db.models import Base
 
 config_alembic = context.config
 if config_alembic.config_file_name is not None: