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.

pyproject.toml

@@ -19,6 +19,9 @@ dependencies = [
     "icalendar>=5.0,<6.0",
 ]
 
+[project.scripts]
+duty-teller = "duty_teller.run:main"
+
 [project.optional-dependencies]
 dev = [
     "pytest>=8.0,<9.0",
@@ -28,7 +31,7 @@ dev = [
 
 [tool.setuptools.packages.find]
 where = ["."]
-include = ["db", "handlers", "api", "importers", "utils", "services"]
+include = ["duty_teller*"]
 
 [tool.black]
 line-length = 120