fix(cli): bootstrap optional CLI dependencies

[smekcio]

Summary

• keep ksef-client as the base SDK install and move CLI-only dependencies to the cli extra path
• replace the eager ksef entrypoint import with a lightweight bootstrap that prints a friendly install hint when ksef-client[cli] is missing
• rename the internal Typer app module to avoid collisions with the public from ksef_client.cli import app export and keep CLI imports lazy
• update CLI installation docs and add wheel-packaging smoke coverage so both ksef-client and ksef-client[cli] are verified in CI

Testing

• python -m pytest --cov=ksef_client --cov-report=term-missing --cov-fail-under=100
• python tools/check_cli_packaging.py

Closes #34