dev: mypy reports missing type stubs and import errors during type checking #320
Description
Running mypy on the codebase produces multiple import warnings.
1. Missing type stubs for icalendar library
tests/conftest.py:5: error: Library stubs not installed for "icalendar" [import-untyped]
tests/test_multiple_vcalendars.py:10: error: Library stubs not installed for "icalendar" [import-untyped]
Mypy cannot provide proper type checking for the core icalendar library used throughout the codebase.
2. Missing type stubs for typer.testing
tests/conftest.py:7: error: Cannot find implementation or library stub for module named "typer.testing" [import-not-found]
The CLI testing utilities lack type information.
3. Local module import resolution issues
tests/conftest.py:9: error: Cannot find implementation or library stub for module named "mergecal" [import-not-found]
tests/test_multiple_vcalendars.py:7: error: Cannot find implementation or library stub for module named "mergecal" [import-not-found]
Mypy cannot resolve imports to the local mergecal package during test runs.